LS1 harness: Start to finish
#101
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Re: LS1 harness: Start to finish
Subscribing and a quick question.
You refer to "commons" e few times. Are these ground wires or just specific wires grouped/connected together?
You refer to "commons" e few times. Are these ground wires or just specific wires grouped/connected together?
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Re: LS1 harness: Start to finish
The pics don't work... Was going to use them for reference while stripping my 89 harness and adapting it to a 01 LS1 harness. Is it on my end or are the pics not hosted anymore?
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Re: LS1 harness: Start to finish
Bandwidth is maxed for the month. Give it a few days to reset. Usually mid month
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Re: LS1 harness: Start to finish
I was wondering about that too as I am about to start my harness and was freaking out a little. The believe the write up should be enough, but the pics you have up are definitely a huge help to all of us. Thanks for the info!
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Re: LS1 harness: Start to finish
Need a few more connectors beyond inj, but s10 4.3 harnesses have most of what's needed
01-02 s10 pcms were 0411 just like late ls1/truck
01-02 s10 pcms were 0411 just like late ls1/truck
#110
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Re: LS1 harness: Start to finish
The S10 PCM will work fine on your 6.0. Using one on mine currently
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Re: LS1 harness: Start to finish
No factory PCMs will work without a tune, so it doesnt matter what it comes out of as long as the service number is compatible. V6 S10s are super common and the 0411 PCM is well established. Ive got a shelf full of them for that very reason
#115
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Re: LS1 harness: Start to finish
Link to wiring diagram I created for my LQ4 swap using 0411 PCM into a 1986 IROC. It uses a Current Performance Wiring fuse block.
https://www.thirdgen.org/forums/ltx-...ml#post5841970
https://www.thirdgen.org/forums/ltx-...ml#post5841970
#116
Re: LS1 harness: Start to finish
*no where did i see anything posted for any intro-newb "redbelly" entry hazing pre-posting?*
i hope that it is cool to belong to this forum?
because i did own the 1984 H.O. w/a 5 speed z-28. wikipedia shows a 305 h.o. only available in the Iroc in 1985 w/an automatic at $11k-13k. well i payed $16K and ordered mine w/the H.O. 305 and a 5 speed in late 1984! it out ran Iroc's with the 5.7 on take off back in the day! i mean the only part i had to replace was the fuel pump and it was a "H.O." that was a few IBs diff from a 305 and basically a 350 fuel pump. i also did have a Pontiac 2001 TA. but it was totaled and it will live on in a truck.
i really was looking for a wiring harness guide to re-wire to engine guide. this diagram/photos are by far the best that i have located. i have several wiring schematic books, but i wasn't there when my engine was swapped. and i am getting the wires redone & the PCM re-prog'd. and i will attempt to re-wire it myself.
i hope that it is cool to belong to this forum?
because i did own the 1984 H.O. w/a 5 speed z-28. wikipedia shows a 305 h.o. only available in the Iroc in 1985 w/an automatic at $11k-13k. well i payed $16K and ordered mine w/the H.O. 305 and a 5 speed in late 1984! it out ran Iroc's with the 5.7 on take off back in the day! i mean the only part i had to replace was the fuel pump and it was a "H.O." that was a few IBs diff from a 305 and basically a 350 fuel pump. i also did have a Pontiac 2001 TA. but it was totaled and it will live on in a truck.
i really was looking for a wiring harness guide to re-wire to engine guide. this diagram/photos are by far the best that i have located. i have several wiring schematic books, but i wasn't there when my engine was swapped. and i am getting the wires redone & the PCM re-prog'd. and i will attempt to re-wire it myself.
Last edited by BayouS10LS1; 11-30-2014 at 07:34 PM. Reason: i'm afraid i will be booted for not owning a gen III, cuz i had a gen IV and now it is in a 1st gen s-10........
#117
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Re: LS1 harness: Start to finish
This thread is a general how-to for building a custom LS1 swap harness. For this to work you still need to have your 3rd gen engine harness cut down to essentially IGN and gauges
Read about it here:
https://www.thirdgen.org/forums/ltx-...p-3rd-gen.html
Now, lets talk about harness selection
You dont have to match your year harness to your year engine. Most of the differences you will be re-doing or replacing. Yes, you can even use the dreaded 98 harness on your 99+ engine/PCM. You also dont have to match the trans type to your engine as the connectors that change between the two are common in junkyards and just as easy to swap out in the harness. All pinouts in this article relate to the 99+ PCMs with a T56 on a 90-92 3rd gen
For broken connector replacement try sourcing a S10 vortec 4.3 harness in a local junk yard. All but about 4 connectors interchange freely and the PCM terminals are the same. If you are super cheap and do not want to buy a 4th gen or 4.8/5.3 truck harness this is a viable option as LS1 style harnesses generally go from $150-250. A pieced together S10 harness with outsourced missing conenctors can be assembled for under $50
This thread will NOT be going over LS1 fuseblocks, dashes or anything other than a plain jane LS1 in 3rd gen swap. A thread covering those maybe in the works for later, but not at this time
For individual circuits, refer here or LS1tech
http://chevythunder.com/
Back to the job, this is a LS1 harness fresh from a 4th gen
This is what you're turning it into. Notice the handful of coiled individual wires. These are all the conenctions to the original harness or the power distribution block
One final word before we get started. Whenever someone talks about the "3 wire hook up," they are talking about these connectors: C100, C101, C105
An exerpt from this article on the subject
http://www.ls1tech.com/forums/conver...swap-faqs.html
Now, down to business. Start by labeling every single connector. If you dont know what one's function is, look it up
Now remove the covers and de-pin both PCM connectors. Some of the pins you will never reuse, others will be easier to lengthen/shorten with them removed. This also fixes any issues with the 98 harness as the pinouts differ greatly
Read about it here:
https://www.thirdgen.org/forums/ltx-...p-3rd-gen.html
Now, lets talk about harness selection
You dont have to match your year harness to your year engine. Most of the differences you will be re-doing or replacing. Yes, you can even use the dreaded 98 harness on your 99+ engine/PCM. You also dont have to match the trans type to your engine as the connectors that change between the two are common in junkyards and just as easy to swap out in the harness. All pinouts in this article relate to the 99+ PCMs with a T56 on a 90-92 3rd gen
For broken connector replacement try sourcing a S10 vortec 4.3 harness in a local junk yard. All but about 4 connectors interchange freely and the PCM terminals are the same. If you are super cheap and do not want to buy a 4th gen or 4.8/5.3 truck harness this is a viable option as LS1 style harnesses generally go from $150-250. A pieced together S10 harness with outsourced missing conenctors can be assembled for under $50
This thread will NOT be going over LS1 fuseblocks, dashes or anything other than a plain jane LS1 in 3rd gen swap. A thread covering those maybe in the works for later, but not at this time
For individual circuits, refer here or LS1tech
http://chevythunder.com/
Back to the job, this is a LS1 harness fresh from a 4th gen
This is what you're turning it into. Notice the handful of coiled individual wires. These are all the conenctions to the original harness or the power distribution block
One final word before we get started. Whenever someone talks about the "3 wire hook up," they are talking about these connectors: C100, C101, C105
An exerpt from this article on the subject
http://www.ls1tech.com/forums/conver...swap-faqs.html
Now, down to business. Start by labeling every single connector. If you dont know what one's function is, look it up
Now remove the covers and de-pin both PCM connectors. Some of the pins you will never reuse, others will be easier to lengthen/shorten with them removed. This also fixes any issues with the 98 harness as the pinouts differ greatly
If it was a 99 harness there would be no need to un pin the two connectors right? You would Just have to remove the wire you don't need.
#118
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Re: LS1 harness: Start to finish
I depinned all of them regardless of year or vehicle class. Read on to where you lengthen/shorten the wires to fit the new PCM location. It'll be 10x harder if you leave them in the connectors
#120
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Re: LS1 harness: Start to finish
Pocket. Wouldn't you just do one wire at a time if you wanted to lengthen them? I think defining the entire connector is way to difficult well atleast for a first time swapper like me
#121
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Re: LS1 harness: Start to finish
Honestly, takes no time to pull a wire out from the ECM connector and to push one back in once you've lengthened it.
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Re: LS1 harness: Start to finish
Hi Pocket,
I've just been going through my harness with a multimeter to make sure the pins all match up to the connectors they're supposed to, and I've completely forgotten about relays.
Do the 0411 PCMs not need relays, or are the relays part of the body wiring that you hook into via the black plug wires that are connected to the c100, c102 etc?
I was thinking that I would need the following relays:
AC
MAF
MAF burnoff
Are there any others I would need, or are these not needed?
I pulled the TPI wiring from the car as well as most of the engine bay wiring when I started my rebuild, so I just need to know what needs to go back in.
I've just been going through my harness with a multimeter to make sure the pins all match up to the connectors they're supposed to, and I've completely forgotten about relays.
Do the 0411 PCMs not need relays, or are the relays part of the body wiring that you hook into via the black plug wires that are connected to the c100, c102 etc?
I was thinking that I would need the following relays:
AC
MAF
MAF burnoff
Are there any others I would need, or are these not needed?
I pulled the TPI wiring from the car as well as most of the engine bay wiring when I started my rebuild, so I just need to know what needs to go back in.
#123
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Re: LS1 harness: Start to finish
A typical LS swap will use FP, Fan 1, Fan 2 and AC
I prefer to run the relays last as they only have a trigger wire to the PCM. Everything else is external to the engine harness
Fuel is simple, PCM triggers the relay, direct to pump
Single fan swaps use the low fan point only
Dual fan cars do ^ as well as a second relay from the high speed point. When the low speed command is enabled, one fan comes on 100% while the second remains still just like 3rd gen fans did. When the high speed command is enabled, but fans engage
AC depends which you use. LSx low mount I use a PCM controlled relay with 3 wire pressure sensor emulating a 98-02 Fbody AC circuit
3rd gen R4 and sanden high mount compressors are wired like 90-92 Fbody TBI AC circuit direct from the HVAC head unit with a PCM reference. The stock hi and low pressure switches regulate pressure
MAF and MAF burnoff relays are part of the 3rd gen wiring and are not reused
I prefer to run the relays last as they only have a trigger wire to the PCM. Everything else is external to the engine harness
Fuel is simple, PCM triggers the relay, direct to pump
Single fan swaps use the low fan point only
Dual fan cars do ^ as well as a second relay from the high speed point. When the low speed command is enabled, one fan comes on 100% while the second remains still just like 3rd gen fans did. When the high speed command is enabled, but fans engage
AC depends which you use. LSx low mount I use a PCM controlled relay with 3 wire pressure sensor emulating a 98-02 Fbody AC circuit
3rd gen R4 and sanden high mount compressors are wired like 90-92 Fbody TBI AC circuit direct from the HVAC head unit with a PCM reference. The stock hi and low pressure switches regulate pressure
MAF and MAF burnoff relays are part of the 3rd gen wiring and are not reused
#124
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Re: LS1 harness: Start to finish
A typical LS swap will use FP, Fan 1, Fan 2 and AC
I prefer to run the relays last as they only have a trigger wire to the PCM. Everything else is external to the engine harness
Fuel is simple, PCM triggers the relay, direct to pump
Single fan swaps use the low fan point only
Dual fan cars do ^ as well as a second relay from the high speed point. When the low speed command is enabled, one fan comes on 100% while the second remains still just like 3rd gen fans did. When the high speed command is enabled, but fans engage
AC depends which you use. LSx low mount I use a PCM controlled relay with 3 wire pressure sensor emulating a 98-02 Fbody AC circuit
3rd gen R4 and sanden high mount compressors are wired like 90-92 Fbody TBI AC circuit direct from the HVAC head unit with a PCM reference. The stock hi and low pressure switches regulate pressure
MAF and MAF burnoff relays are part of the 3rd gen wiring and are not reused
I prefer to run the relays last as they only have a trigger wire to the PCM. Everything else is external to the engine harness
Fuel is simple, PCM triggers the relay, direct to pump
Single fan swaps use the low fan point only
Dual fan cars do ^ as well as a second relay from the high speed point. When the low speed command is enabled, one fan comes on 100% while the second remains still just like 3rd gen fans did. When the high speed command is enabled, but fans engage
AC depends which you use. LSx low mount I use a PCM controlled relay with 3 wire pressure sensor emulating a 98-02 Fbody AC circuit
3rd gen R4 and sanden high mount compressors are wired like 90-92 Fbody TBI AC circuit direct from the HVAC head unit with a PCM reference. The stock hi and low pressure switches regulate pressure
MAF and MAF burnoff relays are part of the 3rd gen wiring and are not reused
I have a TBI AC compressor with the 3 pin plug on it, but using an old OLD school HVAC from the 70s that I'm modifying, and it just has an on/off switch and fan speed switch so I have to wire it from scratch.
From what I can gather, I need a relay for the fan on the condenser, one for the compressor, and pressure cut off switch, does that sound about right?
#125
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Re: LS1 harness: Start to finish
http://www.austinthirdgen.org/mkport...al_V8_vinE.jpg
Thats about as universal as it gets. 12v goes from the HVAC head unit to the compressor clutch with feedback to the PCM. Hi/lo pressure switches break continuity if the pressure is outside of the acceptable range
High pressure switch is on the rear of the compressor, low switch on top of the HVAC box
Thats about as universal as it gets. 12v goes from the HVAC head unit to the compressor clutch with feedback to the PCM. Hi/lo pressure switches break continuity if the pressure is outside of the acceptable range
High pressure switch is on the rear of the compressor, low switch on top of the HVAC box
#126
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Re: LS1 harness: Start to finish
I couldn't find it in here, I'm swapping a 4.8 in to a 86 iroc. Just wonderig if some one could tell me roughly how long the harness needs to be from the back of the motor to inside the car. I'm ok with it being a little to long. I just don't have my car here and wanna get the harness finished. Thanks
Oh and pocket this is awesome
Oh and pocket this is awesome
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Re: LS1 harness: Start to finish
I couldn't find it in here, I'm swapping a 4.8 in to a 86 iroc. Just wonderig if some one could tell me roughly how long the harness needs to be from the back of the motor to inside the car. I'm ok with it being a little to long. I just don't have my car here and wanna get the harness finished. Thanks
Oh and pocket this is awesome
Oh and pocket this is awesome
From memory I think it was an extra 1-2 foot would give you the length, but that's only if you're routing the harness the same way.
I'm using a commodore harness for mine and going straight through the firewall so that I only have to extend the CKP and that's it, but I guess depends what you're doing with the harness route.
Also, probably wait for someone who knows successfully completed theirs and not my advice :P
#128
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Re: LS1 harness: Start to finish
2.5' to mount it on the HVAC box, 3' to fit in the stock location via hole under the HVAC box, 7' stock route behind the fender
#130
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Re: LS1 harness: Start to finish
Hi.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
#131
Re: LS1 harness: Start to finish
Greetings Pocket, I too want to be a wire twisting hippie,
But from what I have found out, I need to go with the latest greatest stuff, which means a 03 s10 blue green harness to start with and a- last of the cable throttle pcms either the 07 express van 801 or the 06 462 because the engine is a 54 tooth reluctor wheel,, when seeing someone say--have the machinest press on a new "exciter ring" they are talking about the reluctor wheel right?
im sticking with the 03-7 pcms because ive heard they are the faster-optimal ones, I know everyone figures the 411 is the most popular but....
one question I have is the possibility of it having the potential to control something like the 12 volt stepper motor VGT mechanism on a Holset he341ve VGT turbo............ I know,, something from way out in left field,,
any possibility? or do I have to plan on adding on a programmable logic controller, like a hobbywing or a picaxe~ if you know what those are.
But from what I have found out, I need to go with the latest greatest stuff, which means a 03 s10 blue green harness to start with and a- last of the cable throttle pcms either the 07 express van 801 or the 06 462 because the engine is a 54 tooth reluctor wheel,, when seeing someone say--have the machinest press on a new "exciter ring" they are talking about the reluctor wheel right?
im sticking with the 03-7 pcms because ive heard they are the faster-optimal ones, I know everyone figures the 411 is the most popular but....
one question I have is the possibility of it having the potential to control something like the 12 volt stepper motor VGT mechanism on a Holset he341ve VGT turbo............ I know,, something from way out in left field,,
any possibility? or do I have to plan on adding on a programmable logic controller, like a hobbywing or a picaxe~ if you know what those are.
#132
Re: LS1 harness: Start to finish
Hi.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
#133
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#134
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Car: 1939 GMC tow truck
Engine: LS1 5,7 corvette
Transmission: 4L80E
Axle/Gears: 4.10
Re: LS1 harness: Start to finish
I found a 2000 suburban 5,3 computer 09354896. Wiring harness i can adapt myself.
It has the drive by throttle cable chip (idle air control) in it.
I just hope that this computer can control the 4L80e gearbox.
Now i only need someone who can customize the software.
It has the drive by throttle cable chip (idle air control) in it.
I just hope that this computer can control the 4L80e gearbox.
Now i only need someone who can customize the software.
Last edited by MTS-rides; 10-26-2015 at 01:02 PM.
#135
Re: LS1 harness: Start to finish
Holy Shyt --what a small world,, I was always into early Camaro's fil my 30's when I went off ol the old GMC tangent, and the ones I mess with are the COE versions of your HD 39, trucks like yours are almost non existant in America now.
http://dallas.craigslist.org/dal/pts/5260229476.html
#136
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Car: 1939 GMC tow truck
Engine: LS1 5,7 corvette
Transmission: 4L80E
Axle/Gears: 4.10
Re: LS1 harness: Start to finish
Holy Shyt --what a small world,, I was always into early Camaro's fil my 30's when I went off ol the old GMC tangent, and the ones I mess with are the COE versions of your HD 39, trucks like yours are almost non existant in America now.
http://dallas.craigslist.org/dal/pts/5260229476.html
http://dallas.craigslist.org/dal/pts/5260229476.html
Saw it neglected for sale in The Netherlands and had to save it.
Stays completely original exterior (fore now)
just needs more power
#137
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Car: 1939 GMC tow truck
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Re: LS1 harness: Start to finish
you can look here:
http://oldgmctrucks.infopop.cc/eve/f.../m/52620155373
Do not want to pollute the camaro ls1 haness forum.
Talking about gmc trucks.
Still need their help when I'm going to make the wiring harness
http://oldgmctrucks.infopop.cc/eve/f.../m/52620155373
Do not want to pollute the camaro ls1 haness forum.
Talking about gmc trucks.
Still need their help when I'm going to make the wiring harness
#139
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Re: LS1 harness: Start to finish
Ive done a lot of searching, and I found some info that I can connect the VATS wire to the Pin 30 on the red PCM connector.
Post #10 https://www.thirdgen.org/forums/ltx-...questions.html Will this work?
I got my new Pocket harness installed this week and was able to fire it up last night but it fires and sounds great for just a few seconds then shuts down. Research leads me to believe its the VATS in the PCM.
Will this work or does it absolutely have to be tuned out as you previously posted?
Post #10 https://www.thirdgen.org/forums/ltx-...questions.html Will this work?
I got my new Pocket harness installed this week and was able to fire it up last night but it fires and sounds great for just a few seconds then shuts down. Research leads me to believe its the VATS in the PCM.
Will this work or does it absolutely have to be tuned out as you previously posted?
#140
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Car: 92 Firebird
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Re: LS1 harness: Start to finish
Hi.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
I have a corvette 5.7 engine wiring harness and computer SERV, NO. 16,232,148.
I have been told. that it can not control a 4l80e transmission.
What computer I can buy the best. Can i use the computer and wiring harness from a 2003 Silverado 5.3 or a 2003 5.3 Avalanche. They are here on a scrap yard in Netherlands.
All tips are welcome.
Either of those truck PCMs should work. Check the service numbers: 9354896/12200411. If all else fails, look for a 01-02 S10/blazer or similar with a 4.3L V6. They all used 0411 PCMs which also work with a reflash
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Re: LS1 harness: Start to finish
Ive done a lot of searching, and I found some info that I can connect the VATS wire to the Pin 30 on the red PCM connector.
Post #10 https://www.thirdgen.org/forums/ltx-...questions.html Will this work?
I got my new Pocket harness installed this week and was able to fire it up last night but it fires and sounds great for just a few seconds then shuts down. Research leads me to believe its the VATS in the PCM.
Will this work or does it absolutely have to be tuned out as you previously posted?
Post #10 https://www.thirdgen.org/forums/ltx-...questions.html Will this work?
I got my new Pocket harness installed this week and was able to fire it up last night but it fires and sounds great for just a few seconds then shuts down. Research leads me to believe its the VATS in the PCM.
Will this work or does it absolutely have to be tuned out as you previously posted?
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Car: 92 Camaro RS
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Re: LS1 harness: Start to finish
I could build one but I'm having trouble making heads or tails of all the bits and pieces of VATS bypass info. I can't find one good thread explaining one or where I hook it to. I also can't get a ohm reading on my 4thgen key. Thirdgen key was 523.
Another difficulty I'm having is clearly distinguishing between thirdgen and 4thgen VATS info. I'm pretty sure my issue is just the 4thgen VATS but I don't understand it all well enough to be sure.
Can you point me to a "how to" thread for building one? Who else sells them besides Hawks? TYIA
Last edited by plum92_camaro; 11-07-2015 at 04:09 PM.
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Re: LS1 harness: Start to finish
VATS is an antitheft system, so its not just annoying it will disable the car. A bypass box will take care of it. The other systems are just annoying and will leave your MIL on until you either fix them (non-existant) or turn the codes off in the PCM. VATS boxes are usually $30-50, $25-30 DIY and a basic swap flash on a PCM $50-100. Not much savings for a DIYer
Ok, lets talk about how VATS works, hopefully itll clear up the modules and resistors questions
VATS is a security system to prevent any goober with a screwdriver from stealing a car. It consists of a resistance pellet implanted in a key and a matching VATS module. Put the proper key in and the module OK's it, then allows the PCM to fire the fuel injectors and starter. There are also two different types of VATS which isnt super important, just remember they're not compatible with each other beyond the key. Reason why a VATS equipped 3rd gen wont work with a VATS equipped 4th gen PCM without extra help
Now to bypasses
The resistor:
If you're running the same system that came with the car ie 3rd gen in a 3rd gen or 4th gen in a 4th gen then you can use a common resistor. GM only made 15 key blanks of different resistance values for all VATS system, so anyone with a meter can measure the original key and solder a matching resistor in before the VATS module. That way VATS is still active but permanently satisfied. Down side is you have to know the original value from the start, so if you just get the drivetrain/PCM you've got a 1/15 chance of guessing it
Next is the VATS module:
When the proper resistance value is given to the VATS module, it outputs a distinct signal to the ECM/PCM to energize the drivetrain. Bypass modules remove the original box and hook up a small box that outputs that unique signal to the PCM. No original info is needed
Tune:
This is the best option because it skips all above and is transferable to any vehicle the PCM is used in. Since there are other things in the PCM commonly changed in a conversion its helpful to clump all these things into one trip to the tuner. With tuners being so prevalent, its not hard to find someone to do this if you lack the software
Ok, lets talk about how VATS works, hopefully itll clear up the modules and resistors questions
VATS is a security system to prevent any goober with a screwdriver from stealing a car. It consists of a resistance pellet implanted in a key and a matching VATS module. Put the proper key in and the module OK's it, then allows the PCM to fire the fuel injectors and starter. There are also two different types of VATS which isnt super important, just remember they're not compatible with each other beyond the key. Reason why a VATS equipped 3rd gen wont work with a VATS equipped 4th gen PCM without extra help
Now to bypasses
The resistor:
If you're running the same system that came with the car ie 3rd gen in a 3rd gen or 4th gen in a 4th gen then you can use a common resistor. GM only made 15 key blanks of different resistance values for all VATS system, so anyone with a meter can measure the original key and solder a matching resistor in before the VATS module. That way VATS is still active but permanently satisfied. Down side is you have to know the original value from the start, so if you just get the drivetrain/PCM you've got a 1/15 chance of guessing it
Next is the VATS module:
When the proper resistance value is given to the VATS module, it outputs a distinct signal to the ECM/PCM to energize the drivetrain. Bypass modules remove the original box and hook up a small box that outputs that unique signal to the PCM. No original info is needed
Tune:
This is the best option because it skips all above and is transferable to any vehicle the PCM is used in. Since there are other things in the PCM commonly changed in a conversion its helpful to clump all these things into one trip to the tuner. With tuners being so prevalent, its not hard to find someone to do this if you lack the software
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Re: LS1 harness: Start to finish
1st question... Can you still load and unload a PCM if you are VATs locked out to tune it out. Or should I tune it out before hand?
2nd... Do you have any pinouts/links/tips on an older 3rd gen(specifically a 1985 z28) It had a factory carb. I assume I have to make some sort of relay/fuse box, for electric fans, fuel pump. Or any sources of schematics? Once I saw links to individual systems breaking it down, it made alot of sense.
The good news, is I have an entire running and driving 2000 T56 ls1 car that I will be getting donor parts from. At one point I am going to gut the ls1 car and junk it, just don't want to regret not getting some stuff.
Other questions, where do you source your wire? what is typically used? 18 and 20 guage? do you just do butt splices and heat shrink if you need to extend it the harness?
2nd... Do you have any pinouts/links/tips on an older 3rd gen(specifically a 1985 z28) It had a factory carb. I assume I have to make some sort of relay/fuse box, for electric fans, fuel pump. Or any sources of schematics? Once I saw links to individual systems breaking it down, it made alot of sense.
The good news, is I have an entire running and driving 2000 T56 ls1 car that I will be getting donor parts from. At one point I am going to gut the ls1 car and junk it, just don't want to regret not getting some stuff.
Other questions, where do you source your wire? what is typically used? 18 and 20 guage? do you just do butt splices and heat shrink if you need to extend it the harness?
Last edited by MustangEater82; 11-18-2015 at 04:28 AM.
#145
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Re: LS1 harness: Start to finish
Tune anything in any order. The PCM wont be any use for a swap unless VATS is turned off though
A carb car will need a fuseblock added to protect the engine electronics. There is a diagram in the additional info thread along with pinouts for every year 3rd gen
I buy wire in bulk in two sizes: 18ga TXL and 12ga TXL. Everything that goes to the PCM is 18ga, heavy cables for power/grounding get 12ga. If you plan to do multiple harnesses, then its worth while to stock up on some new wire. For just one, Id grab a cheap mid 90's GM harness to scavenge wire from. S10, CK truck, van etc. For splices, I use a modified lineman splice; strip one end about 1/2" then the other about 1". Twist the two together for the 1/2" then fold over the remaining exposed 1/2" and twist again. This often pulls the wire slightly short, so tug it back to length and it will slightly unravel. Pinch it tight, solder, cover and youre done
A carb car will need a fuseblock added to protect the engine electronics. There is a diagram in the additional info thread along with pinouts for every year 3rd gen
I buy wire in bulk in two sizes: 18ga TXL and 12ga TXL. Everything that goes to the PCM is 18ga, heavy cables for power/grounding get 12ga. If you plan to do multiple harnesses, then its worth while to stock up on some new wire. For just one, Id grab a cheap mid 90's GM harness to scavenge wire from. S10, CK truck, van etc. For splices, I use a modified lineman splice; strip one end about 1/2" then the other about 1". Twist the two together for the 1/2" then fold over the remaining exposed 1/2" and twist again. This often pulls the wire slightly short, so tug it back to length and it will slightly unravel. Pinch it tight, solder, cover and youre done
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Re: LS1 harness: Start to finish
Hey Pocket,
Sorry I think I've asked before, but just wanted to double check, what relays are needed for the LS1 PCM?
There's no MAF / MAF Burnoff?
Only Fuel Pump?
Sorry I think I've asked before, but just wanted to double check, what relays are needed for the LS1 PCM?
There's no MAF / MAF Burnoff?
Only Fuel Pump?
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Re: LS1 harness: Start to finish
Fuel, Low fan, Hi fan (optional), AC (optional)
If a fuseblock needs to be added then an IGN relay is also required
If a fuseblock needs to be added then an IGN relay is also required
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Re: LS1 harness: Start to finish
ok i got my harness almost done but i have one black wire that goes to the pcm but cant figure out whre it goes. any help
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Re: LS1 harness: Start to finish
Is it a black wire pinned in to the PCM and you can't figure out where it goes?
Or is it a black wire in the harness and you don't know where it goes on the PCM? If so, we need to know where it is attached to the harness at the other end.
Sounds like it is a ground for something simply because it's black, but lets not assume.
Or is it a black wire in the harness and you don't know where it goes on the PCM? If so, we need to know where it is attached to the harness at the other end.
Sounds like it is a ground for something simply because it's black, but lets not assume.