[kyle.browningg]

Changed the GPR and now truck will turn over but wont start. I started having a problem with electrical issues. Truck would run but die on its own after 10 mins of idle but now to the point it won't start. Turn the key and relays under dash click.
With key off, I have 13.5 volts on the big constant post of the gpr and 0 volts on the other 3 posts like normal. With the key on I have 13.5 volts on the big constant post and 0 volts on the other big post, 7 volts on the little front post and 7 volts on the back little post which is the ground. Could I have a bad pcm now? These issues are throwing me for a loop

 

[Oneof6]

Certain you are getting full battery voltage to the firewall harness? There is a small junction box on the DS fender that the DS battery cable connects to the firewall harness. If corroded or loose it will cause an undervoltage condition and many odd issues. A 5 minute easy check to eliminate.

 

[kyle.browningg]

Yeah, I checked it and it was clean and tight. No issue there

 

[panhead george]

Changed the GPR and now truck will turn over but wont start. I started having a problem with electrical issues. Truck would run but die on its own after 10 mins of idle but now to the point it won't start. Turn the key and relays under dash click.
With key off, I have 13.5 volts on the big constant post of the gpr and 0 volts on the other 3 posts like normal. With the key on I have 13.5 volts on the big constant post and 0 volts on the other big post, 7 volts on the little front post and 7 volts on the back little post which is the ground. Could I have a bad pcm now? These issues are throwing me for a loop

If I remember correctly,
You are supposed to measure 12vdc to ground on both "little posts". When you turn the key "ON", one little post is supposed to be grounded from the PCM signal to the GPR. You have to make sure which post. 7vdc is a low measurement. I determined which post is the signal from the PCM and have a pushbutton to ground that post when I turn the key on. I also DISCONNECTED the wire on the GPR post that comes from the PCM. I count the seconds and release the button.

If you remove the signal wire from the PCM at the GPR, and ground that post, you should be able to measure 12vdc (to ground) on the glow plug side of the GPR... for a test ...
If you do not have smoke from the exhaust while you are cranking, the HPOP is not working, or the LPOP is not feeding oil to the HPOP.
If it is cold and you have fuel (smoke) out the exhaust while cranking, use your engine block heater. It will start without the glow plugs if the oil is warmed.

Get a scanner, AE or Forscan. Find your codes. It will save a lot of guessing and money. Once you become familiar with how your engine works, it is a less stressfull and less expensive.

You also need to put information in your signature. It helps everyone see what you have so they can help when you post.

 

[kyle.browningg]

I was wondering, will a 99 pcm work in a 02 model? I still haven't found the problem but figured I'd swap the pcm if they're interchangeable and give it a shot instead of buying a brand new one in case it's not that either. Also haven't been able to get communication from the obd2 port which is a bummer because I can't pull codes.

 

[klhansen]

Take it a step at a time.
If you've got relays clicking when you're trying to start, you have a high resistance connection somewhere between the batteries and the rest of the electrical system. Check ALL the battery connections, including ground side (at the engine block). Once you've confirmed you have good voltage everywhere, then check the starter. It may be drawing excess current and pulling voltage down. If you can't communicate thru the diagnostic port, check the fuse to the cigarette lighter. And NO, a 99 PCM won't work in an 02. Your problem is NOT the PCM.