Duramax intake heater

One of the best places I've found for Dmax info is

Buzz

Greetings,

I'm not sure exactly what you are referring to about an "intake heater". My '04 LB7 uses glow plugs to preheat the cylinders prior to start-up. Cummins diesels used to (still do?) use an intake heater grid. You may have an intake heater if you have the cold weather package, but I never see those here in Florida...

If your "Wait to Start" light remains lit after start-up then you have either a glow plug problem or a controller problem. If power remains on to the glow plugs for any great length of time it will more than likely fry them as they are not intended to be fed constant power. My WtS light remains lit for only a few seconds for a cold start and may not even light up at all on a hot start.

Time to go see a trained mechanic.

Good luck - Jonathan

I guess I'm confused as to what I have. When I told someone my glow plugs are not working, they told me that I didn't have glow plugs I had an intake heater. So I just thought they knew what they were talking about. Some people are like that they always stand there and tell you all kind of stuff, only to find out later it was BS.

Anyhow there must be a relay somewhere that I can use as a starting point to find out whether it is trying to work or not. I know that something (glow plugs or intake heater) is not working as good, because although it still starts, it doesn't start as well.

I'd be willing to be that "someone" owns a Dodge...

Anyhow, open your hood and on the driver's side you will see the underhood electrical center - a square plastic box over the wheelwell with a snap-on top. Remove the top and you will find the panel for the major relays and fuses. On the inside of the lid is a diagram of the placement of these relays and fuses, and there should be a major one for glow plugs, probably a relay. I'd start by replacing that one. However, the ECM is what actually controls your glow plugs so anything having to do past replacing the relay you will need more technical diagnostic equipment. The ECM may take its input to turn on the glow plugs from the IAT (intake air temp) sensor or the CTS (coolant temp sensor) so that is something to consider down the road.

Since your truck starts but not well, I think that you may have some fried glow plugs (which might be expected by now if you have an older unit) and the light is staying on to let you know that that's the problem.

Good luck - Jonathan

The light only comes on until I start it, I noticed that the light didn't go out in a couple of seconds when it was a lot warmer out. Now that it is colder I left the switch on for about 5-10 seconds and it still doesn't go out, at least until I started it. I can't believed my glow plugs are burnt out, because it has never sat around with just the switch on and it only has

Thanks for the information about the relays, I thought I would post this before I even look under the hood. Hopefully it is something simple, I have an OBD II scanning tool that maybe something will show up on that too.