Heritage Z

iTrader: (4)

The bird is what I removed the harness from along with the ac delete box. I'll have to look at the harness alittle later and check the wires against some diagrams. I have a barbeque to go to that I'm late for.

I'll let you know what I find. Thanks for the help.

Heritage Z

iTrader: (4)

Looks like someone deleted the ac. All the wires match the fuel, ac and fan relay wires. Looks like I will still have to wire in a second relay for the fans.

Thanks I appreciate the help.

1hotbird

Hey Pocket

Can you please clarify something for me?

With the speedometer wiring? I am putting a 1999 LS1 into 1987 Firebird 305 4 barrel carb auto.

On the Ls1 the speedo wire is already run from the trans to the ECM. inside the engine harness.
From C220 (K) on the ls1 harness. What do I do with it from there?

Do I remove the buffer box? or just hook it to C207 (D) and the green wire on the buffer box?
Do I cut the green wire? Thanks

Pocket

iTrader: (24)

The VSS goes to the PCM, then the PCM sends it to the speedo

Connect the output wire to C207 pin K (brn) then remove the buffer box and connect pins C and F together

1hotbird

Thank You!

If you don't mind what the best way to hook up the factory tach?

rock861261

the factory tac for the ls1 comes from the serial wire and 3rd gen is r10 on ls1 and a13 on lt1

1hotbird

Sorry I'm not following? On the LS1 the tach is hooked to the serial bus data?
Is there a way to make the factory tach work in the 3 gen?

Do I need a tachometer interface?

HP52TA

iTrader: (4)

I am just finishing up the internal connections of my swap and was QAing my wiring when I came across this in your write up.

As the stock wiring from the buffer to the speedometer does not go through C207, I was struggling with your use of Pin K of C207. After reviewing the schematics, I see this does work just fine with the jumper you identified.

This was of course after I connected it in a different manner. I connected the output from the LS1 PCM, R50 direct to the Lt. Grn/Black wire going to the speedometer connection 14 / C1 at the instrument cluster. I also "T" this connection to provide a pulse signal to my 4th Gen Cruise control unit, which is going to Pin "K". Does this "T" connection cause any degradation of the pulse train to the two devices?

Thought I would add the schematics (89 Firebird manual) to help understand this connection.

rock861261

For a ls1 swap and to use the stock 3rdgen tach you would use pin R10

Pocket

iTrader: (24)

Correct, strait from the LS1 PCM to your tach. Remember, stock LS1s output in 4 cyl mode, so have your tuner change it to V6/V8 mode to match your tach

No loss of signal from one extra module. This is a relatively short DC circuit, so the signal is pretty powerful for what it it

1hotbird

I'm not seeing the output wire from my ls1 harness to hook up the 87 firebird coolant gauge? Do I need to use my original sender or dose it hook the the LS1 Harness?

Just got back in the house from starting the LS1 for the first time! It runs Good! I used the cars oil pressure gauge to monitor that and EFI Live scan tool to see all the other gauges. Sounds nice with open exhaust!

1ADan

iTrader: (4)

a typical ls1 harness does not have this output on it. however, there is an easy fix. the 98 fbody used a 3-wire sensor (instead of the 99+ 2 wire setup) for coolant temp. 2 wires for pcm use, one for gauge.

1hotbird

I have a 99 LS1. In the original car how dose the dash get the signal from the engine?

Because I already have the old engines coolant sender would it be easier to install that in the passenger side head and wire that in?
Just remove the block off plug and install the sender.?

1ADan

iTrader: (4)

the dashes got their sensor data from the pcm serial bus as opposed to directly from the senders like older cars. i opted to swap the 2 wire sensor out for the 3 wire to cut down on the amount of harnesses and sensors sticking out everywhere. the sbc sensors also dont fit the hole in the head, so you'd need to get an additional adapter if you're looking to go that route.

1hotbird

Good Info! Thank you!

1hotbird

edit

1hotbird

Ok I'm up and running now. all gauges look to work, except the Tach
It reads 0 all the time. What PCM Pin# goes directly to the tach?

Dose it need to be tuned so that it works?

I know it needs to be tuned to read v-8 vs 4 cyl so I expected to see half the actual RPMs.

Thanks

I also hooked up the evap system but looks like my purge/vent valve is not working. have to drop the tank back out and see. Glad I don't have exhaust on it yet!

Pocket

iTrader: (24)

These questions dont belong in this thread, but just the same, 99-04 LS1s use R10 for tach. Bird tachs are more sensitive and usually require a booster wire. Use a 680ohm resistor along a fused 12v wire to the tach signal wire. General rule of thumb, wrong tach = value change in the PCM. No tach needs booster wire

1hotbird

Sorry

LsxMatt

iTrader: (4)

Can this be done with a carburated harness too?

1ADan

iTrader: (4)

of course, my 87 was originally carbed and I used this as a very useful guide (thanks again Pocket!). There are subtle changes over the years, engines, and body types, but the process is pretty much the same. I highly recommend getting a hold of the factory service manual (or at least some good Alldata pinouts) for your specific year and model just for back up.

LsxMatt

iTrader: (4)

Ok thanks. Im just trying to wrap my head around how exactly this works. How much of the 3rd gen harness is being pulled from the car? Because after it comes through the firewall, it goes into the under dash fuse box, and then the gauges and to the computer. So i am pulling the entire harness including the under dash fuse box all the way to the computer?

My car is an 86 carbed sport coupe.

five7kid

iTrader: (14)

The computer harness is on the passenger side. You use what's in the driver side. You don't have to remove anything under the dash (except the ECM).

If you want things like speedometer and OBDII connector, you will be doing some work under the dash, though. There are also some little things like brake switch (auto trans) or clutch switch (manual) that are good to connect to the PCM as well.

LsxMatt

iTrader: (4)

So the harness going out the passenger side to the engine bay is being removed and not being reused? Then the driver side harness is what going to be mated to the ls1 harness?
Just want to make sure i understand everything. Thanks

five7kid

iTrader: (14)

Pretty much. My LS1/4L60E car had an '86 LG4 system swapped into it back in '99, including the dash.

I really got into the LS1 swap:




What the driver side engine harness came down to (plus the oil pressure and engine temp wires):

LsxMatt

iTrader: (4)

Ok i understand now. I didnt know the two harnesses were seperate being they were connected by loom near the a/c box. Got them seperated and i can see what you are talking about. I have the pcm harness on the left, the driver harness on the right, and the a/c wires coming out the firewall in the center.

Please excuse the mess. Im currently prepping the bay for paint.


So as for the driver side harness, the factory fuse block is being entirely cut out and what wires that are kept are being routed to the cadillac fuse block?

rickyzZ28

iTrader: (4)

You will still use the factory harness on both sides for some items. You need to look at the pinouts for your year car to figure out what will be used from the C100 plug on the drivers side. On newer swaps there are about 8-10 wires that are reused like the starter wire and misc power wires, oil pressure, but I am not sure about older swaps. Also some of the stuff from the passenger side will end up being used as well. They will connect to the C207 if your car has one under the dash on the passenger side.

LsxMatt

iTrader: (4)

I just realized that the wad of wires on the drivers side firewall is actually a connector before it goes into the car/interior fuse block, AKA C100. I thought it was a regular grommet like the passenger side, which was why i thought the interior harness had to come out. Well that clears up alot.

I'm gonna order a service manual to get the exact pin-outs for my car, then ill know exactly what i want to remove and keep. Thanks again for all the help.

LsxMatt

iTrader: (4)

I ordered a service manual online today so ill have the correct c100 and c207 pin-outs for my year. As far as removing unused wiring, am i keeping the alternator wiring, or is the alt wiring from the LS1 harness going to be used instead? Also, is there a wiring diagram around on how to wire up the fuel pump? Being my car is carbuerated i don't have any fuel pump wiring going to the tank.

1ADan

iTrader: (4)

Pocket, hope you don't mind me posting this one up (I can pull it if needbe):


the fuel pump is run through the engine/pcm harness, this was the same layout I used for my engine fuse box. This is the "stand alone" wiring setup; guys with TPI/TBI may go a different route and use some of the stock fuse box, this keeps things a little simpler for diagnosing

90-irocdx3

iTrader: (4)

Anybody know where pocket has been, i tried contacting him a while back. i needed to see if he can clean up my harness. shows he hasn't logged in since 4-09-12

Flip 2

iTrader: (1)

About 6-8 weeks ago, he told me he was so swamped with his regular job he wasn't taking any more work on until Summer.

Ozzie'Z28

Hey Pocket I am currently doing a swap myself and I am ready for wiring. I am a lil confused because at the fender grommet I only have 3 wires a blk a green and a blue. I have what is called a piggy back harness I bought from Hawks and has all the plugs for the engine but I have wires that are color coded the same color as behind the firewall on the c-100 connector. Is that where I have to connect to or am I missing something. The wires I'm talking about are: "check engine lite","speedo","oil pressure switch","tach",12v for a/c",and there is a purple one that is not labeled,not sure what is for though. If you can help me or route me in th right direction I will appreciate it much. I bought engine transmission and PCM from same car so that is a match.

Pocket

iTrader: (24)

Thats not the fender grommet, its the HVAC connector. BLK is fan motor ground, lt blu AC request from headunit to PCM, dk grn/wht is the coolant fan override which isnt used any longer

There is an external red wire that supplies 12v battery to the system you need to find and connect

Check engine light aka MIL is in the C207, BRN/WHT
Speedo is in the C207 GRY or BRN for 90-92 camaros and 86-92 birds. Older years are mechanical and require a mechanical driver box such as cable-x

Oil press TAN C100
Tach WHT C100
12v AC wont have a specific wire, I like to use the PNK/BLK emissions wire from the C100
If the PPL wire is 12ga, it goes to the starter solenoid. If it is 18ga, it is the brake switch input for the PCM. Both are from the C100

My first response would be to call hawks, but seeing how much of his work Ive fixed in the past, itd be easiest to answer the questions now

FIRECHICKEN

iTrader: (3)

Ok maybe i missed somethig? I get most of this so far. More or less. The thing i dont get is the red and orange wires going to a power distribution block on the passangers side of the engine bay. Is this because the camaro has the battery over there? My 89 Formula has a battery on the drivers side. Should my power distribution block be over there?

Also on my car my two fan relays are on the passengers side.

So should i not really use any of the pictures are a reference?

Thanks

Pocket

iTrader: (24)

Put them wherever you want. I find it easier to keep them close to the battery

Remember, you can move the battery if needed

FIRECHICKEN

iTrader: (3)

I'm probably goin to move the battery to the trunk anyway.

robertfrank

iTrader: (27)

I have a quick question. I have a friend of mine with an 89 that was originally a tbi car but the previous owner did a half a$$ LT1 swap. The stock tbi computer is still in the stock location and the LT1 computer is in the engine bay. He's running a Painless harness for his fans so what all do we need from the stock engine harness? How could I make him a very bar bones harness from whats left of the stock harness? what can I remove?

87oldschool

Hi Pocket thanks for all the informative thread responses. Although asked I have never seen you respond to this question. I am an original owner of an 87' Camaro 305/t-5, 355/t-5 and finally 388/T-5. I have just put my car back on the ground after a 14 years in the air. I am planning/schemeing an LS3/T56 swap in the next 30-60 days. Would you do a conversion harness for me, what would you charge and finally how long would it take? I am obviously not in a great rush. Currently, I am modifying a factory K-member for the corvette front acc. engine. My plan is to get as much done before hand.....I have done the battery relocation to hatch area but not wired yet.
Thanks so much,
Carl 336-707-2328 (87OldSchool)

Pocket

iTrader: (24)

Im not building harnesses anymore, sorry

87oldschool

Thanks for the quick response and I am sorry to hear you are out of the harness business. I much prefer supporting members than lining the pockets of the big boys!
Good luck and thanks again.
87OldSchool

91z28 98ta

iTrader: (1)

I have stripped my 3rd gen harness down to the essentials and I am good with everything except the fuel pump relay wiring and need help. In my 89 5.7 tpi iroc c100 I have E6 and G4 as fuel control wires. Ok so the G4(tan and white) is going to one side of relay coil, a black and white going to other side as grounding. Then I have a orange(12v) and red wire (fuel prime?)that or normally closed and a blue wire from old cpu. so after relay energizes it connects 12v(orange) to blue wire?? If g4 suppose to be signal to pump why is it on coil side of relay? This g4 was also connected to oil psi sensor so I know I have the right relay.what the heck is going on? and what does E6 go to anything on ls harness?? Thanks in advance

FIRECHICKEN

iTrader: (3)

From my understanding. The red wire doesn't do anything but act as a jumper wire from the aldl to "test" the pump. You will be deleting it when you switch to obdII aldl any way. The tan wire goes from the relay and to the fuel pump itself. The orange is 12v supply. I'm not sure about a blue wire but mine has a green wire that is a signal wire from the PCM to activate the fuel pump relay. The oil pressure sensors is wired into the tan wire to supply 12v as a back up incase the fuel pump relay should fail. I deleted the oil pressure sensor wires that feed the pump. Black is ground obviously. That's it I think??

Lurbie

iTrader: (3)

I don't see a blue wire either. Here's a portion of the 89 schematic for the FP Relay

91z28 98ta

iTrader: (1)

Yeh that schematic is the same as I have but the orientation of my wires makes no sense to me. My tan and white wire is coming of of the coil side of the relay instead of the contacts side. I will post a pic. I understand relay logic very well I may just delete this and wire up one that makes sense

Pocket

iTrader: (24)

Nailed it

Repin it properly or replace it. If it's the old flat relay, I'd replace it anyways

91z28 98ta

iTrader: (1)

Scratching my head as to why its different it is untampered with and all factory. If G4 is the correct location to supply 12v to pump I'll just wire up one....does G4 connect inside car to fuse box before pump?

Lurbie

iTrader: (3)

OK so I know you said you were at the right relay, but it really sounds like you're looking at the MAF relay. Look on the right side of that same schematic. It has the blue wire you have and it has the Tan/Wh wire on the coil side.

91z28 98ta

iTrader: (1)

U sir are correct after pocket quoted flat relay I realized I indeed had the maf relay.for some reason I was thinking the one I had was correct because it was tied to the oil psi when I cut the commons out it kinda screwed me up..thanks for getting me straight guys

BadboiJR13

Would a "Megasquirt" harness work together with a stock harness when doing the swap? Pocket