Well, after reading all the various posts, I was really wondering what my problem was..

I have an '04 January production LLY 2500HD crew. I'm in Ontario Canada, and since November I've been having a really hard time starting the truck, and poor mileage. (maybe 25% less in town and 10% less on hwy). (but in general I get under 11 liters/100 km on the hwy, driving 100 km/hr, which translates to about 24 mpg imperial at 64 mph, or around 20 mpg US....hope that helps you non-metric types....btw, the whole world uses metric....)

Starting below -16C is impossible. Starting below -8C very difficult. Starting above -6 is no problem at all. When I say impossible, I mean I can try turning it over repeatedly over the course of an hour, and rarely get a cough.

incredible volumes of black/white smoke during cold starting....a real hazard to my neighbours.

Also, it takes 45 seconds or so for the glowplug indicator light to go out....but when the engine is warm, it;s out instantaneously .

When I use the block heater, for at least 1 hour, I am *always* able to start the truck, so the block heater is critical right now, being January.

Anyhow, I'm thinking faulty glow plugs, and possibly injectors.

After reading the posts, I understand there is a flash upgrade for the fueling system.

Anyhow, dealer informed me today that the Glowplug module is toast, and a new one is on order. Injectors passed testing, thank goodness. The idea that at 22000 km I need major engine repairs was not thrilling me.

Also, GM forces the flash upgrade on service, so I've been flashed.

Get the truck in the morning, hope all is well with the new code. I am hopeful and sceptical at the same time.

I like reliability, I hope GM didn't make a lemon for me.

Your Glow Plugs are OK, but your Glow Plug Control Module (GPCM) was locked up. 2004 vehicles produced in December '03, January '04, February '04 and a few in early March '04 have GPCM's that have a software problem that can cause the module to lock up. The new module will solve your cold start problems and your excessive smoke after cold start...

Mine had the same problem with the temps at around +40deg F. Glow plug module was replaced and now no problem. See if yours has a yellow dot on it. It is located on the drivers side of the engine back towards the firewall on top. It's a black box about 3.5 inches square. You can also try to unplug the connectors on it for a minute and then reconnecting them again. This may get it working again temporarily. Thanks JimmyDel for this info on a previous post.

thanks for the information...

I'll check the module for the yellow dot.

Got the truck this AM and it is a world of difference to have a working glowplug system. really fast (2 seconds?) glow plug turn off delay, even starting in -22C this morning! Fantastic.

I do notice less power now with the flash upgrade :confused:

I guess all that means is --- get the juice.

The old module will have the yellow dot. The new one will have the green dot. I'm not sure about the flash upgrade. Mine has been to 2 dealers for service items and no reflash. I'm not sure I want it since everything is running fine except for parking lot surge which isn't that bad...yet.

Where in Ontario?

Had to replace mine right after it was new. Glow plug light came on and stayed on but I could tell they weren't working. New module and problem solved.

FYI,


I did get my module finally replaced. The error code that was reported was U0106.

Things seem to working well, even in the deep cold.

regards--