No CEL?

[S 854]

My check engine light doesn't light up with the key in "run" and the engine not started...

My first diesel here... All my previous gasser cars and trucks would show the CEL when I turned on the keyswitch prior to starting the engine...

Haven't tried yet but I'm gonna loosen the fuel cap on the drive home to see if the CEL is even working... Good idea?

Or is the CEL out a normal setting?

 

[chevyburnout1]

Gas cap wont set a light on a diesel. No evaporative emissions monitors. But you are right. The CEL should illuminate for a short bit when you go key on, engine off. That'll even fail you if you need emissions in Colorado. What year is your truck? The ECM controls the CEL circuit directly to the cluster for most years.

 

[C.bowles2]

Could mean a bad ECM. Had a duramax in for no crank no start that wouldn't illuminate the CEL. Diagnosed it for a new ECM




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[S 854]

Jumped in last night for the trip home and the CEL lighted...

Started and ran the truck for a few minutes then shut it down... the CEL didn't come back on with the keyswitch...

Let it sit for about 5-10 minutes and the CEL worked again...

Normal?

 

[c20elephant]

What year truck helps so would a code #, EGR's are known to set a CEL and clear a few days later and even within hours on the next startup. (mine did before any modifications). But until you can post a code we are just guessing....

The EFI V2 will pull 4 parameters of codes, some set the CEL and some do not....

F-1 EPA current DTC

F-2 EPA pending

F-3 MFG set DTC's

F-4 MFG all DTC's

 

[chevyburnout1]

If I'm understanding right the OP is just wondering if the CEL should do a "bulb check" at key up. Nothing to do with codes. But it sounds normal to me. From what I've seen doing diesel emissions testing, the GM trucks won't immediately re-illuminate the CEL after a quick key cycle. I believe the ECM has to power down before it will illuminate again on the next key cycle.

 

[THEFERMANATOR]

After running the truck, you have to shut the key off for at least 30 seconds for the ECM to fully power down and reset for the next drive cycle. Otherwise it thinks its on the same drive cycle, and it won't illuminate the CEL since it has already illuminated the light for that drive cycle. And I believe the CEL is an led for all duramax's, so its unlikely for one to go out.

 

[c20elephant]

The cluster can be R&R in about 30 minutes to change the bulbs (maybe it's not a bulb after reading Fermans post). Except me as I'm dangerous around plastic upholstery panel clips, dash panels, body panels, clip type electrical connections etc. so I have to real careful....:spit:

There is a guy here in town that can rebuild my cluster in about an 1-1/2 hours at my house, that's all he does...

 

[S 854]

Yes... Wondering whether or not the CEL bulb worked...

This 30 second reset of the module sounds like what I'm experiencing...

Thanks guys...