Glow plug indicator on for over 15 seconds, MIL illuminates, no DTC code reports


New member
Dec 10, 2010
Temecula, CA
Went to start my '06 Silverado 2500 (LBZ) the other day. Turned ignition on and the glow plug coil light came on, which is strange for this time of year in Northwest Arkansas. Stayed on well past normal time, even in freezing temperatures. I went ahead and started the vehicle, and the coil light went out, truck started just as normal, but the MIL came on and stayed on. Put the code reader on it and it shows "no codes detected". I chose to erase...even though there was nothing there. It continues to illuminate even when I choose to erase what won't report.

I've gone through the "normal" use of the code reader, which has worked previously on this vehicle many times...including indicating failure of all of my glow plugs). I replaced all 8 glow plugs about three years ago with AC/Delco OEM units and it's been flawless until this moment. indication of any malfunction or operation of the truck when I start or use it.

I'm a bit frustrated at this point because I don't know what to check because there is no DTC recorded. Do I just have a bad code reader? Is this something that indicates a problem but my admittedly basic code reader is a cheapo that I've had for over 10 years and is just a POS? Searched the forum but can't find anything that shows an MIL illumination without actually throwing a readable code.

If all else fails, I'm happy to purchase another reader just to check that angle, but would love any input if it's something anyone has encountered...and preferably, solved.