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AC Bingel
10-27-2003, 20:33
I just installed a set of quick heat glow plugs on my 99 Suburban, the old ones had 100,000 miles on them. The truck was hard to start in the mornings with a lot of smoke upon start up. The new glow plugs did not help. Is there a way to test the glow plug controller? I suspect this might be the problem.
LanceW
10-28-2003, 05:20
Unplug the Coolant Temp Sensor, it should give you a long glow cycle.
BuffaloGuy
10-28-2003, 05:35
Best test is to pull a glow plug, ground the threads with a alligator clip and a wire. Then hook the glow wire back to it and turn your ignition on. It should glow cherry red (in the shade).
moondoggie
10-28-2003, 09:21
Good Day!

I don't think your truck has a Glow Plug Controller - I think the PCM directly controls a Glow Plug Relay. At least that's how my 95's work.

Blessings!

Brian Johnson, #5044
AC Bingel
10-28-2003, 13:22
I believe I do have a glow plug relay. It is mounted on the fire wall. Is it recommended to change it when new glow plugs are installed?
moondoggie
10-28-2003, 14:49
Good Day!

To test the Glow Plug Relay, you want to measure the voltage drop across the Relay while it is providing power to the glow plugs. Hook one test lead of your meter (DVM: doesn't matter which one; analog meter: red lead) to a positive battery post, the other test lead to one of your glow plugs. Have someone turn your ignition key to the "run" position, where you normally turn the key to let the glow plugs heat before cranking the engine - do NOT crank the engine. Observe the meter while the glow plugs are supposed to be on - in a perfect world, you would see 0V. I've never done this test myself, but I suspect you'll see a small voltage, but it should certainly be < 0.5V.

Pay attention to what you
charliepeterson
10-29-2003, 19:51
You will find fuseable links coming of the controller going down to the plugs. The links should be close to the controller and one does the DS and the other does the PS. Inside the underhood fuse box you will find a 10amp GP fuse and a 20amp eng. fuse going to the GP controller.

The glow plug controller is behind the fuel filter.