Glow Plug

[Defender]

Did a quick search but couldn't find any answers so......I have a 2003 GMC 2500HD. We have been having some very cold nights in the Phoenix area. Low 20's in my area. The check engine light came on and is throwing P380 which from past experience is a glow plug problem. However, in the past the check engine light stayed on until repairs were made. Now, it goes off in the afternoon. My question....do I have a real glow plug issue or is the extreme cold messing with me?

[DmaxMaverick]

You probably have one or more bad plugs, or the (controller) relay is failing/failed. The PCM will only light up the SES lamp on the second consecutive GP fault, but will clear the lamp after a couple "warm" starts (DTC remains in history), when the ECT is high enough to not command a GP cycle monitoring. The same can happen with the intake heater (often the same DTC), but it isn't at all common, other than a relay failure.

Test/replace the plug(s) or relay, or just ignore it until it's convenient to do something about it. 20°F isn't near cold enough to worry about it.

[Defender]

Thank you sir. Will take it in.

[More Power]

I have heard from a few owners now who reported difficulty in removing the original glow plugs. In the worst cases, the head(s) had to be replaced because of broken off glow plugs and damaged heads. So, don't twist them off if they are being difficult. Let a professional do the work. In any case, be sure to use a good anti-sieze on the threads of the new plugs.

Jim

[CoyleJR]

Defender, I live in Fountain Hills, AZ. and was having the same problem you are having. My Edge programmer indicated that #8 glow plug had failed. I replaced the glow plug and the problem was solved.
Good Luck
John