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Help please

also check the condition of your grounds. for an automatic tranny truck there should be three smaller wires connected to the intake studs near the passenger side of the engine close to the trans dipstick tube. there will also be a few grounds on the inner fender by the passenger side battery too. I would recommend removing the grounds on the intake and cleaning them good, reinstall them. make sure the block to frame ground wire is in decent condition. there is one down by the starter on the frame (flat woven strap) there's more, I just can't remember where there all located.

but mainly the ones on the intake are for the PCM (powertrain control module). and clean the battery terminals while you have them disconnected :)
 
something that just came to mind. just for precaution. I have read but not experienced it myself that the IP sometimes when have failed can send the engine into redline rpms. a fuel or oil leak making it's way into the intake can do the same causing a runaway engine. in this event the only way to shut it down is to choke the engine and kill it if turning the key off doesn't. pull the air filter and tube from the truck where you have room to place a wooden clipboard or something hard and flat that won't get sucked into the turbo where in this event you can completely cover the turbo inlet and choke it and stop it from running away. but do NOT use your hands or rags to do this!!

removing the air filter and tube you also need to make sure there is nothing in that area, dirt, leaves, hoses or anything that is loose that would possibly get sucked into the turbo and destroy the engine.
 
vaughn8993 said:
13,17,18,19,22,25,29,35,37,39,43,46,49,57,62,63,78,84,91,92,94,95,96,98
Click to expand...

Start with code 57. PCM 5 Volt Shorted

Everything else on the 5 Volt circuit is No 💩 broken: Because it doesn't have 5 Volts to it anymore. So the Stupid ECM pukes out a bunch of codes because things are not working. Yeah, but, Shorted 5V is why.

You have several codes for say the APP, Accelerator Pedal Position (APP) 1 Circuit Low , Glow plug relay, boost sensor on the manifold... and they all need a or several 5V reference(s) to work.

You will need to unplug things until the Code 57 is no longer "current" and active. If that doesn't do it you are looking for a shorted wire. Inspect the harness under the intake and the fuel filter assembly.

Check fuses. This means pull every single one out, inspect, clean blades and put back in.

Both batteries disconnected and load tested.

Grounds as mentioned is always a good idea to clean.
 
Last edited:
WarWagon said:
Start with code 57. PCM 5 Volt Shorted

Everything else on the 5 Volt circuit is No 💩 broken: Because it doesn't have 5 Volts to it anymore. So the Stupid ECM pukes out a bunch of codes because things are not working. Yeah, but, Shorted 5V is why.

You have several codes for say the APP, Accelerator Pedal Position (APP) 1 Circuit Low , Glow plug relay, boost sensor on the manifold... and they all need a or several 5V reference(s) to work.

You will need to unplug things until the Code 57 is no longer "current" and active. If that doesn't do it you are looking for a shorted wire. Inspect the harness under the intake and the fuel filter assembly.

Check fuses. This means pull every single one out, inspect, clean blades and put back in.

Both batteries disconnected and load tested.

Grounds as mentioned is always a good idea to clean.
Click to expand...
So I cleared codes and cleaned the grounds and when I went back to check it just keeps flashing 12 and that’s it but it is still idleing at 2200 RPM on startup and stays there rock solid and when I put it in gear it starts surging and the rpms go way down then back up almost sounds like a cam in a gasser
 
Good Catch @WarWagon

@vaughn8993 one simple way to check for 5v reference is to use a digital volt meter. you can probe to one of the sensors that is listed in the codes like the coolant sensor that is mounted on the thermostat crossover, the yellow wire provides 5v and the black is ground. other sensors work the same. probe the 5v wire and a good ground like the frame or body. watch the voltage on the meter as you disconnect each sensor on the engine one by one. if there is a shorted sensor, once you disconnect it, the meter should immediately read 5 volts or there abouts. I will look online and post a link for the wire schematic that might help
 
Begin with OS/ CPS TEST recommend above.

Having a spare pmd for this type of diagnostics is a requirement for this rig. Like having a spare tire- you just need one. Some people just throw it in the glove box, imo a mistake.
Have the pmd on a heatsink mounted front bumper. Mount the spare on a second heat sink next to the one in use. Only buy a lifetime warranty pmd. Drive on it and use an old known good as the spare. Buy the premade or diy a plug with silicone to plug into the spare in order to keep the contacts clean.

NEVER hook one up without a heatsink. A second or two can burn a good new one up!

Why have it mounted ready to go? Because cold winter stormy night on the freeway is not when you want to have to mess with those 4 tiny screws. Swapping the plugs takes 5 seconds. Then you are on your way.

When the lifetime warranty one dies, swap to the other one. Then when you can, you send the warranty one in for replacement. Then put the new replacement back into use asap and keep the spare as the spare. Obviously if both are lifetime warranty- doesn’t matter which is in use and spare.

ANYTIME electrical is acting oddball, swap the connectors and you know instantly if it’s the pmd.

Removing and cleaning all the engine grounds needs to be a regular service task for these -really any GM rigs. I am a chevy guy, but GM electrical systems suck, and we have the worst grounding of any manufacturer. How often depends on your environment. I am in Vegas, 1930’s cars with original paint parked outside their whole life have no rust here. People in the rust belt should make it an annual task. A weak ground will send the whole system bonkers
 
I will not drive my truck out of town without a spare PMD. I thought I was going to be using the truck to haul that old Dodge over to Wyoming for the BIL so I finally ordered a PMD, and the spare heat sink and plug.
My son insisted that I use his new Dodge W3500 to drag the trailer to Wyoming so now I do have the spare unit if I need it.
I did not yet get the HS mounted with the PMD attached and plugged and now it is below zero out there so it might not get done for a couple of days.
Oh yeah, I think that there are rubberish plugs that can be obtained for those weather pack terminal plugs. I think I’d rather use those than to silicone the plug shut.
 
You don’t put silicone on the spare pmd. Put it in a spare connector.

Blue Hummer used to sell them for a few bucks. Idk if anyone else is making them. You can just buy the connector online or at a parts store.

It is a good idea to use a dab of dielectric grease on the contacts of this and all your connections, especially if you live in a rusty environment.

6EBBEA89-FBDF-404E-BDE3-AA79EADAEBFF.jpeg
 
MrMarty51 said:
I will not drive my truck out of town without a spare PMD. I thought I was going to be using the truck to haul that old Dodge over to Wyoming for the BIL so I finally ordered a PMD, and the spare heat sink and plug.
My son insisted that I use his new Dodge W3500 to drag the trailer to Wyoming so now I do have the spare unit if I need it.
I did not yet get the HS mounted with the PMD attached and plugged and now it is below zero out there so it might not get done for a couple of days.
Oh yeah, I think that there are rubberish plugs that can be obtained for those weather pack terminal plugs. I think I’d rather use those than to silicone the plug shut.
Click to expand...

I haven't had a spare PMD since I bought my truck in 2010. The recent IP purchase included a PMD which I harvested. My son will properly attach it to a heat sink and I'll get a spare harness for it.
 
vaughn8993 said:
It’s been moved to an external but I ordered a new one last night. Should be here Sunday. I ordered a whole new relocation kit just so everything will be new
Click to expand...
Some of those harnesses are made in commiechina. They dont work so well. Many people have had issues of breakdowns after they were installed.
The most reliable source for the harnesses is leroy diesel or Quadstar Tuning. Same with the PMDs.
 
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