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glow plugs not working

2K views 16 replies 4 participants last post by  greasemykey 
#1 ·
Have an 02 excursion and for some reason even after replacing both valve cover harnesses and the module i still have not glow plugs. Any ideas on what else it could be?
 
#2 ·
How do you know they're "Not Working"?

You've replaced everything so I'm gonna assume the problem is with the Module not getting activated by the PCM. I would probe the Modules pins to see what's going on. Maybe unplug the EOT and see if that makes a difference (the PCM may then see the need a bad sensor was covering-up)
 

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#4 ·
What's that code?

Below 40 and not starting without the block heater doesn't sound like a GP problem. You shouldn't actually need Glow Plugs at all unless it's in the "teens", it might be a hard start but it Will Start. Using the Block Heater is all about thinning the oil (are you using 15W dino or 5W synthetic?).

How many miles on those Injectors?
 
#11 ·
OK so, All 3 codes come back with the same diagnoses...

Open/grounded circuit, open/shorted GPCM, failed PCM :(

You've replaced the module, to Me that kinda leaves a problem with the wiring between the PCM and the Module OR it PCM itself...

I would think, since the PCM recognizes a problem and generated codes, that the EOT sensor is OK because it's saying that the PCM is trying to activate the module but knows it's not working.

At this point you'd need a wiring diagram and it's time to start checking those connectors and tracing wires...

Diagrams here -> BBB Industries - TSB's & Wiring Diagrams ....OR ->
Vision-OE - Free TSB's & Wiring Diagrams
 
#13 ·
before i get out into the snow i looked at the wiring diagram listed on one of your recommended sites. is there a fuse or relay that sends power to the GPM? if not im going to have to pin it out with my power probe until i find the wire that does not have power. if i searched on here correctly the black and orange stripe wires on each plug should have power KOEO and so should the red wire.
 
#14 ·
one quick question. i have power where i think i should on the module. but the manual that i bought said that trucks equipped with a GPM also have replaceable fuseable links in each wiring harness. where are these fuses?
 
#15 ·
The fuseable links are just "fancy" wires that are made to open at a pre determined amperage if it's exceeded. Follow the wires from the GPR to the battery. If you have battery power at the GPR then at least one of the fuseable link wires is good.
 
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