Need lq4 wiring help!
Thread Starter
Teching In
Joined: Oct 2009
Posts: 5
Likes: 1
From: Alberta, Canada
Need lq4 wiring help! Hi, I'm new to the site and am just starting on a project. I want to put this LQ4 in a 72 Chev pickup. I already got the motor, the problem is that when I got the motor the guy had hacked the wiring harness. I got the computer, throttle body, etc. but I need to get a new harness to modify. The engine came out of a 2004 3500HD truck. What vehicle can I get the wiring harness, throttle pedal, and TAC module from? The number on the computer is 12580786. Also would anyone have a pinout diagram for this. I talked to a wrecking yard to get this stuff but I need to know what one will work. I would just get the engine wiring harness to modify? Sorry for all the questions but I want to start off on the right foot. Thanks for any help.
harness cmcdonald, i think after 2003 gm's 4.8,5.3,6.0 came drive by wire, you will need a drive by wire harness with the matching pedal, tac, maf sensor.it will be good ifthe ecm all come rom the same vehicle. also gm made different connectors for the injectors(3 types). you have to make sure they match up. i would go drive by cable to bypass needing a tac & foot pedal. just purchase a throttle body thats drive by cable. this site will also lead you to the wiring diagrams. i swapped a 5.3/4l60e in an '87 c10. i stayed with drive by wire and found out that the foot pedal is not sending a signal to the trhottle.
Teching In
Joined: Jul 2006
Posts: 37
Likes: 0
From: altoona,pa
cmcdonald, I am doing the same swap w/ a 71 chevy. I am having some problems on what headers to run, do they make a specific set for this swap, or do I have to run something from a camaro or truck?? If you have not gotten this far and you can find out let me know. Or if you can tell me what you are running with yours Id really appriciate if you could let me know.Thank you in advance for any help or advice you could give me. Ill post anything I learn.
TECH Senior Member
Joined: Jul 2009
Posts: 8,032
Likes: 661
dec010974 is correct DEC010974 is correct regarding matching the TAC Module and Pedal. Most people I know, if they didnt get the tac module and pedal from the donor vehicle, will just run Drive By Cable as it will save you some money. Just remember that the tune in the PCM has to reflect this, typically at the same time, the people swapped to the older 411 PCM tuned for a 02 Camaro throttle setup. Hope this helps.
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'Dont Let EFI Pass You By!'
87 c10 to all those converting to ls1,ls2,lq4,lq9 with 73-87 c10. this my situation. not 100%, but headers used will be trial and error. i purchased pacesetter and jba's and stuck with the jba's. jba's resemble factory exhaust. with the pacesetter headers i would've needed to notch the frame on the driver side and cut of the egr valve and plug on the passenger side. some say brphotrods headers will fit but, by the time you order, send back, then reorder again time has been wasted. with that said, factory exhaust will work fine. all you need a good muffler shop to bend the driver side manifold away from the frame rail. and your good to go. here are pics of shordee.
