'95 LT1 out of a Trans Am into an '86 Firebird and I cannot get the fuel pump relay to fire. I have the green/white from the LT1 PCM hooked to the signal, power coming from a switched source, ground and output hooked up right but still won't fire. I can jump the relay from a 12v source and it will click the relay and fire it. I measured the voltage coming from the signal wire and it is around 9.7 volts. I contacted someone who measured the voltage from a car that I actually plugged my PCM in to program the vats and egr out of it and it would start the car and let it run with my PCM after the re-programming and he measured 10.1 coming from the signal wire to the relay. This really has me stumped, the only thing I do not have is the C100 plug out of the PCM hooked up which has the power to the injectors and ignition, is it possible that this is causing the problem? I have tried 3 different relays, the original that came off of the 86, a universal 12v 4 pole relay, and a direct replacement for a 95 Trans Am.

 

PCM A7 should trigger green white wire make relay work if you have power going right to pcm. Pins B15, B31 orange wire hot all times
B30 D3 Pink wires into PCM key on and off ingnition power those up. Check all grounds on PCM make sure there good. On newer relay like 4th gen uses ON relay diagram 30 goes ingnition same wire feeds B30 D3 or long as it keys on and off has 12volts. 85 should be green white wire be from PCM. 87 to fuel pump. 86 ground of chassis. From what I can recall I think c100 just would put power to injectors on shouldnt affect fuel relay as long as you get ingnition and battery power pcm should trigger key is on. Might as well wire injectors up too they come in handy

 

Hmm...I'll check this stuff when I get home, I have all the grounds from the harness grounded to the body, I have an always hot to the orange wire on the black 4 wire connector, switched power to the pink wire on the....blue connector if I remember and I am getting voltage on the green/white wire, it just won't close the relay. I've tried 3 different relays so far, but if I jump the 30 to the 85 pole (without the PCM hooked up) the relay will close and the pump will come on.

Am I right in there only being one power wire going to the PCM which is the black 4 wire connector that has the big purple crank wire as well?

Thanks for the info and any other assistance would be great.

 

Heres is diagram may help you look pic 3 http://shbox.com/1/4th_gen_tech2.html#1995_pcm_pinouts

 

Well, got the motor going tonight, on the 95 model, the BAT to PCM wire is actually in the C100 connector, the underhood fusebox and plugs I got for the blue, white, and black connectors came out of a 94 and are totally different.

No BAT power to the PCM, no PCM signal to anything to make it work

It's the little things like this that makes a person feel small. But it's running using the underhood fusebox for the fans, ignition, injectors, and AC and not one piece of the old wiring that comes from the passenger side fender is in the car.

Thanks for the help on this Deathtrap, I appreciate it alot

 

Good deal you must be blending LT1 harness in with stock V6 or V8 harness? Thats what I did wasnt to hard to do. I used iso relay sockets from injector.com instead stock relays on a third gen
Sockets nice clip your fuel, fans, AC etc all together and tuck them out of sight.

 

Actually, the only thing left of the original harness is the original C100 connector and that's it, the rest is gone and it's all running on the LT1 harness and underhood fuseblock from a 94 Z28 to run the fans, ac, injectors and ignition....just one main pink wire from it to switched power for the injectors and ignition, and another orange/black to switched power and that's it. Everything else is spliced into the C100 connector with the exception of the tach wire since my V6 dash had idiot lights I spliced it in under the dash, same with the VSS output wire for the speedo.

 

Thats same way I did mine I was worried I would mess it up but it was easy to do once I knew what all wires were out of bulkhead. Im glad to see old V6 go. LOL Except its been sitting here in garage for 2 years cant find anyone wants it.