DennisG01

I'm a little confused - can anyone help? I have no codes and the engine seems to start fine in cool temps (40*F). It cranks for about 2 seconds and then fires up. Runs smooth and I don't see any white smoke. So everything seems to be working fine with the glow/starting system, but...

Just for kicks I ohmed the glow plugs (this truck is new to me and my experience with diesels has been GM trucks, so far). I connected my meter to a good ground and then to each pin at the glow plug controller's connector (I removed the connector from the controller to do this).

For each of the six plugs, I had zero ohms. Meaning, not "infinity" or "open" - exactly the same as if I would touch my meter's two leads together. I thought that plugs should have about 1.5 ohms?

Fourdiesel

Depends on how sensitive your meter (digital?) is. My Fluke digital general purpose VOM reads about 0.5 to 0.6 ohms for a good glow plug. Most glow plugs fail open circuit when they fail but some show 10-100 ohms and are still 'bad'. Most times the engine electronics will throw a MIL when a glow plug is out of spec. The engine will still usually still start fine unless it gets really cold.

DennisG01

My meter (you are correct - it's digital) isn't on par with a Fluke, but it's a pretty decent one. When I would test the plugs in my old GM 6.5 TD, a good one would usually be in the .8 to 1.2 range. I expected to at least see something on these plugs. The 0.0 reading really threw me for a loop. But since ALL of them measured the same, maybe it is just my meter? I csn try another meter (Fluke) that I can borrow from a friend.

alx

Plugs rarely go bad. Your plug controller is going to go bad every few years. If you have a slow start (long crank before catch) try the following- turn the ignition to position 2 but don't start the engine. Wait until the glow plug indicator goes out plus 10 seconds. Crank. If engine starts much faster- it is your plug controller.

On resistance- unless you read open you don't know if plug is bad. Depending on where it failed in the winding inside A bad one can read just like a good one (but not heat up at all). Lucky for us star/ das usually picks up stored codes pointing to bad plugs. However a bad controller does not show so use the procedure above to determine if it died.

DennisG01

Longer time to heat the combustion cylinder - got it. Before I had more glow time programmed into my 6.5's ECM, I would sometimes do a couple key-on/key offs to do the same thing. Occasionally, I would unplug the ECT sensor which would trick the ECM into thinking it was -40*F and give max glow time.

We can get stretches of 15* to 20* F temps here in PA, with dips to 0* - just want to make sure everything is up to snuff before those temps start to hit.