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‘04 GTP electrical problems?

A

AwGarage

New member
Hi, I’m new to the forums and was hoping to get some help before I get started.

Little back story on the car:
I really purchased a 04 GTP as a little project car. So far what I know about it(what the previous owner told me and my quick walk around). I was told it needed headgasket and that it didn’t start due to that. Now I’m familiar with the 3.8 and 3.4 motors and I knew that shouldn’t cause the no start problem.

Long story short, it cranks over fine but doesn’t start. I’ve pulled a decent amount of codes with my obd:
P0030 - Heater Control Circuit
P0036 - H02S Heater Control Ciruit
P0201-6 all injectors are bringing up a open circuit
P0243 - Supercharger wastegate solenoid A
P0443 - Purge curge control valve circuit

I was hoping to get some opinions before I start looking deeper into it, finishing up another project right now and would like a head start into this one. My guess is maybe the fuel injectors ground is bad or the PCM? But willing to listen to others who’ve pulled similar codes and what fixed their problem or point me in the right direction.
 


Most of the "grounds" on these cars are total sh*t from the factory. For me, first step would be to go through every ground in the engine compartment and re-do them. Particularly bad ones are the fenderwell right next to the battery, ICM right underneath the coil bracket, and the ground strap from the starter side of the engine block to the body.

That could fix some of the problems, I'd also check the harness from the injectors going all the way to the PCM. It could easily be as simple as a broken wire somewhere. And it's rare for a PCM to just go bad, usually it's because of a mistake while tuning it (losing power while writing to it and bricking it) or physical damage/water damage. Not unheard of, but highly unlikely.
 
Actually.. I think those all share a power. Injectors always have power and are toggled by the pcm for ground. I'd start by checking fuses. Testing for power at injectors with key on.
 
Messed around with it a little bit today, the fuse for the fuel injectors( believe it was B2) doesn’t have power with key on.(none of the fuses above it had power either they were all 15 amp fuses). Checked the connector at the pcm and going by the pinout I’ve found online, pin 4,5,6,7,10 all have power(not sure what voltage since I wasn’t able to use a multimeter only a test light/probe and the light was very dim) but pin 9 doesn’t seem to have any power which I believe is pin for the #2 fuel injector control. If all fuel injectors are powered by the same source which wire is it? Any diagrams?
 
^ thanks I appreciate that. I wasn’t able to find the fuel injectors diagram(maybe because I’m on mobile, I noticed somethings loaded while others didn’t). Is it true that every injector is powered by the same lead? Is the pcm just a ground for them?
 


fuel injector control is NEGATIVE aka ground. It's going to be tough to get power off a ground.

What you should do is find the turn on/relay that gives the injectors power. Basically trace back the power from the injectors.
 
Does anyone have a diagram for the wiring going from the fuse box to the pcm? I know all the injectors are separate at the pcm but which wire do they lead to before the fuse box fuse? Because I have no power at the fuse box for the injectors so I’m assuming I should start follow the wires from the fuse box back to the pcm.
 
Pretty sure PCM doesn't turn on power to the fuse, the key does. Pull your fuse box forward and look at the two wires going to that fuse, now find the relay it goes to etc.

FWIW Scottydoggs says that libraries usually have repair manuals with the schematics. You can also search google and likely find an image of the one you need.
 
Okay I’ll check it out^

Messed around with it a bit, the coils aren’t getting power either. So I was going to look into the ICM but figured it’s kinda odd for both the fuel injectors and the icm don’t have have power. Any ideas? Maybe a shorted fuse box or pcm?
 


Besides suggesting the same thing again? Nope, this is still what I'd do and it would be quick and easy.

BillBoost37 said:
fuel injector control is NEGATIVE aka ground. It's going to be tough to get power off a ground.

What you should do is find the turn on/relay that gives the injectors power. Basically trace back the power from the injectors.
Click to expand...
 
Okay I’ll start pulling back the fuse box and chasing the wires. Was thinking about it earlier, could it be possible for the crankshaft position sensor to be messing with it? That would explain why the coils aren’t getting spark and I believe that’ll mess with the fuel injectors correct?
 
Power to injectors etc is independent of the crank sensor. Sorry..

If you look up the electrical diagrams and understand what they tell you, you should be able to go straight to the right circuit. Otherwise I'd read the fuse box and see which fuse says injectors and go that way.
 
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