5.3 LS - Third Generation F-Body Message Boards

Engine Swap Everything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.

5.3 LS

Reply

Old 10-10-2018, 06:39 AM
  #1  
Junior Member
Thread Starter
 
Join Date: Aug 2018
Location: South Carolina
Posts: 36
5.3 LS

Picking up a free 5.3L LS with heads. I know there are deep threads with builds. I was wondering what people though on single or twin turbo build or something else.
OGLEGEND is offline  
Reply With Quote
Old 10-10-2018, 09:39 AM
  #2  
Supporter/Moderator
iTrader: (6)
 
ShiftyCapone's Avatar
 
Join Date: Feb 2001
Location: Cincinnati, OH
Posts: 11,474
Re: 5.3 LS

Originally Posted by OGLEGEND View Post
Picking up a free 5.3L LS with heads. I know there are deep threads with builds. I was wondering what people though on single or twin turbo build or something else.
Whats your goal and what is your budget?
ShiftyCapone is offline  
Reply With Quote
Old 10-10-2018, 10:36 PM
  #3  
Senior Member
 
freaky's Avatar
 
Join Date: Nov 2010
Posts: 930
Re: 5.3 LS

what wiring harness is everybody using . im looking into painless . jus wondering what everybody else is using ?
freaky is offline  
Reply With Quote
Old 10-11-2018, 09:05 AM
  #4  
Supreme Member
iTrader: (8)
 
Join Date: Sep 1999
Location: NJ
Posts: 2,509
Re: 5.3 LS

Originally Posted by freaky View Post
what wiring harness is everybody using . im looking into painless . jus wondering what everybody else is using ?
A lot of people use a re-worked car or truck harness, but those are almost never plug and play. Painful is generic too, so it would be similar to any other stand alone. There are some who make plug and play harnesses here
scooter is offline  
Reply With Quote
Old 10-11-2018, 03:41 PM
  #5  
Senior Member
 
freaky's Avatar
 
Join Date: Nov 2010
Posts: 930
Re: 5.3 LS

does sumone make an adapter to adapt the inside harness to the truck computer ?
freaky is offline  
Reply With Quote
Old 10-11-2018, 03:58 PM
  #6  
Supreme Member
iTrader: (8)
 
Join Date: Sep 1999
Location: NJ
Posts: 2,509
Re: 5.3 LS

Hawks will graft your truck harness to the harness for the car for $1,000. or you can read the swap guide and do it yourself.
There are people here that will build a new harness too
scooter is offline  
Reply With Quote
Old 10-11-2018, 04:57 PM
  #7  
Member
iTrader: (3)
 
LsxMatt's Avatar
 
Join Date: Jul 2011
Location: New York
Posts: 467
Re: 5.3 LS

Psi Conversion makes a great harness, thats what I used. It comes pre loomed and its basically plug and play. Plug in your pcm, attach a ground to the head and power terminals to the starter and you’re good to go. Only really extra wiring you have to do is connect your fuel pump wire to the relay block provided with the harness. I’ve had one in my car for about 4 years now, no issues. They’re relatively cheap too, I paid 580.00. You can get them in auto or manual, vortec or ls style, and dbc or dbw configurations as well.

Id personally stay away from the painless harness. My buddy ordered one for his caprice and the thing comes without loom, basically a big spagetti mess, more PAINFULL than anything. He also paid way more than the 580.00 I did as well. He never got the car running with that harness and eventually gave up and ordered the psi one. Car started right up.
LsxMatt is offline  
Reply With Quote
Old 10-12-2018, 12:43 AM
  #8  
Senior Member
 
freaky's Avatar
 
Join Date: Nov 2010
Posts: 930
Re: 5.3 LS

Originally Posted by LsxMatt View Post
Psi Conversion makes a great harness, thats what I used. It comes pre loomed and its basically plug and play. Plug in your pcm, attach a ground to the head and power terminals to the starter and you’re good to go. Only really extra wiring you have to do is connect your fuel pump wire to the relay block provided with the harness. I’ve had one in my car for about 4 years now, no issues. They’re relatively cheap too, I paid 580.00. You can get them in auto or manual, vortec or ls style, and dbc or dbw configurations as well.

Id personally stay away from the painless harness. My buddy ordered one for his caprice and the thing comes without loom, basically a big spagetti mess, more PAINFULL than anything. He also paid way more than the 580.00 I did as well. He never got the car running with that harness and eventually gave up and ordered the psi one. Car started right up.
with the psi one does the interior guage cluster plug into the computer to or is it all new both under the hood an under the dash ?in case you hadnt noticed wiring is my weak area .i got message from painless an theres is jus for the under hood part . they said guages wouldnt work. if i use the truck harness an computer do you repin the interior part of the wiring ?

Last edited by freaky; 10-12-2018 at 01:14 AM.
freaky is offline  
Reply With Quote
Old 10-12-2018, 08:39 AM
  #9  
Supreme Member
iTrader: (8)
 
Join Date: Sep 1999
Location: NJ
Posts: 2,509
Re: 5.3 LS

Originally Posted by freaky View Post
with the psi one does the interior guage cluster plug into the computer to or is it all new both under the hood an under the dash ?in case you hadnt noticed wiring is my weak area .i got message from painless an theres is jus for the under hood part . they said guages wouldnt work. if i use the truck harness an computer do you repin the interior part of the wiring ?
There are "3" gauges that indicate from any engine, and one that may come from the computer. Oil pressure, water temp and RPM. Water temp and oil pressure on a gen 1-3 engine come from the sensors, you need to connect those to your C100. The RPM on a gen 3 and 4 (probably 5 too) comes from the ECM, you would have to connect that to the tach wire on the ECM too. Really, this is all covered in the swap guide. you need to start reading

​​​​​​​https://www.thirdgen.org/forums/engi...third-gen.html
scooter is offline  
Reply With Quote
Old 10-15-2018, 11:02 PM
  #10  
Member
iTrader: (3)
 
LsxMatt's Avatar
 
Join Date: Jul 2011
Location: New York
Posts: 467
Re: 5.3 LS

Originally Posted by scooter View Post
There are "3" gauges that indicate from any engine, and one that may come from the computer. Oil pressure, water temp and RPM. Water temp and oil pressure on a gen 1-3 engine come from the sensors, you need to connect those to your C100. The RPM on a gen 3 and 4 (probably 5 too) comes from the ECM, you would have to connect that to the tach wire on the ECM too. Really, this is all covered in the swap guide. you need to start reading

https://www.thirdgen.org/forums/engi...third-gen.html

The C100 harness is the one coming out of the firewall right next to the brake booster. That harness stays! It has all the wires that go from your gauge cluster to the sensors on the motor. It also contains the power terminals that connect to the starter which feed 12 volts to all of your interior accessories and lights. It also takes ignition power from the starter connection and is what will crank the motor. I've seen a few people just rip out all the old wiring then wonder why the car won't crank. The harness that is getting removed completely is the engine harness that connects to the pcm through the bulkhead connector in the passenger lower fender, right below the antenna pass through. I used a how-to by Pocket on here showing how to prep the C100 harness. It basically shows how to clean it up and remove any un-wanted wires. I think the only ones I was left with was the headlight harness, wipers, oil pressure, coolant temp, main power terminals and purple wire going to the starter.

There is no complete plug and play harness as far as gauges go. But as for getting the car running, minus the gauges, the PSI harness is the easiest and best priced one out there IMO. For my gauges, I ended up using the ls coolant temp sensor and just hooked the stock thirdgen wire to it. It reads low by about 10 degrees, but I've been driving the car for close to 5 years this way so I know exactly where the gauge is supposed to stay. For oil pressure, I believe I used the stock ls1 f-body sensor. Perhaps 1998, but I'm not 100%. This reads accurately with my 92 gauge cluster. Another thing you can do is just use a thirdgen oil pressure sensor. I was doing this at first, I just used some 1/4 pipe thread adapters from the hardware store. You could also just tap the oil cooler hose block off plate on the left side of the oil pan and screw the thirdgen sensor in there. I mean its pretty simple, all you'll really have to do is at most extend the 3 thirdgen gauge wires to the appropriate sensors on the motor, and hook them up accordingly. All the happy time vroom vroom is going to be taken care of by the engine harness you choose. Just remember to KEEP the driver side harness by the brake booster. It's separate from the harness on the passenger side going through the fender, minus a few connectors you just unplug from the C100 booster harness I believe.

Also the PSI harness has the tach and speedometer wire right at the pcm connection. They leave them in an extended section of wire with the OBD connector, so you literally just run them from the harness to your cluster. The harness also comes with relatively detailed instructions on how to hook it up, as far as what wires need what on the PSI side. So hooking up the speedo and tach to it are simple. The hardest part is figuring out which wires to tap into coming out of the cluster. Check out these wiring diagrams, they'll have everything you need.

http://www.austinthirdgen.org/index.php?pid=19
LsxMatt is offline  
Reply With Quote
Reply

Thread Tools
Search this Thread
Advertising
Featured Sponsors
Vendor Directory
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: