cycling glow plug issue

[bigblockfever]

hey everybody

I just put a glowplug controller on a 7.3 idi. The wait to start light will come on for about 3 seconds (even if it is ice cold)then turn off. It will then continue to cycle on and off really quick. Does this sound like a wiring issue or is the controller bad? I could really use a direction with this.

PS the truck did not have a controller on it. I took one off a parts truck. all the wiring was still there in the truck just no controller.

thanks!

 

[IDIBRONCO]

First, check your glow plugs to see if any are burned out. If they are all good, then it could be the controller.

 

[franklin2]

You either have some bad glowplugs, or bad wiring connections going to the glowplugs.

The controller uses the current draw of the glowplugs to determine glow time. As the glowplugs warm up, they draw less current, so then the controller will cut them off or cycle them on and off.

If you have just one that is burnt out, it will think the glowplugs are already hot because of the less current draw from the one bad glowplug. So it will turn off early and cycle the plugs.

Poor connections at the glowplug tips to the wires will also cause this. Poor connections allow less current flow. So again, the controller thinks the plugs are already hot and cuts them off and cycles them.

 

[JakeUlch]

Experienced a similar issue and as everyone has said check the wire connections and the plugs themselves, you want to make sure you have motorcraft glow plugs, and I saw thewespaul has a new harness you can buy if the wiring from the controller to the plugs looks wonky