Looking for some help figuring out what is going on

[Ethan M]

Yesterday I went to change out the drive side injector return lines and I unbolted the bale connectors but did not unhook them. After I went to start the truck my oil pressure gauge wouldn’t work and my edge wasn’t lighting up. As soon as I touched the screen my glow plug light would come on and stay on. Shut the truck off and went thru and found a plug behind the a/c compressor that had come undone. Plugged it back in and my oil pressure worked again and the edge come on with the key. Now I’m getting codes for no communication to ecm and glow plugs are not working now. Any ideas? Any wiring diagrams I can check?

 

[Ron Nielson]

Download the electrical manual here: Note that the manual covers 2003-2006

https://www.gmupfitter.com/wp-content/uploads/2021/05/2006_LD_CKFullSizeElectrical.pdf

 

[2004LB7]

Try resetting the codes of you can first. Then see what comes back

 

[Ethan M]

U0100 keeps coming back and p0113, tried unhooking battery clearing codes. Those keep coming back and the glow plug light doesn’t come on anymore

 

[2004LB7]

p0113

Inspect the harness running to the MAF/intake air temperature sensor sensor and check for any chaffed, shorting or broken wires. Might also be from a bad sensor too

 

[Ethan M]

Thanks I will check those. What triggers the glow plugs to come on? Does it have to be a certain temp before they will?

 

[Ron Nielson]

https://static.nhtsa.gov/odi/tsbs/2015/MC-10113715-9999.pdf

 

[2004LB7]

Thanks I will check those. What triggers the glow plugs to come on? Does it have to be a certain temp before they will?

If the line to the MAF temperature sensor is broken the ECM will think it's -30° outside so command glow plugs to be on longer