Glow plug controller?

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Jan 23, 2014 | 10:58 PM

#16

19887.3IDI

Freshman User

Joined: Jan 2014

Posts: 29

Likes: 0

From: Michigan

My truck does this too. The wts light comes on for the normal 15-17 seconds and goes out but the controller still heats the glow plugs for another 15-17 seconds after the wts light goes out and stays on constantly doesn't cycle on and off.

Im pretty sure its not the controller because I have replaced it. I have checked all my wires and they look fine none of them are getting warm or anything. I even ran a new 6 gauge wire form the battery's to the controller and its still does the same thing. I did notice if I unplug one glow plug (doesent matter which one) the system works as it should with the 15-17 second wts light and the cycling after the light goes out.

My glow plugs have about 20,000 miles on them and they are motorcraft ZD-9's. Starts right up though no problem even in Michigan's latest arctic weather.

Jan 24, 2014 | 11:09 PM

#17

speedwrench72

Posting Guru

Joined: Dec 2012

Posts: 1,065

Likes: 2

From: western washington

the late module controller should only heat the gp's for 120 seconds then turn off, even if the engine is not running. replace it. remember the power source to the controller is on all the time when key is on. power that is switched by the controller to operate the gp circuit is the high current (big wire) that comes from long post of the fender mounted starter relay. your controller see's the temp, if it see's no heat in the gp's it will behave funny check to be certain that the gp's are getting current