Ok I think my glow plug controller is going bad but I want second opinions. Every morning my truck starts fine even below 20 with one cycle of the plugs. Once the truck is warm though the plugs don't cycle when I start it. Which is fine when I start it shortly after I shut it off. But after an hour or two the truck won't start because it needs the glow plugs but they still won't cycle. I have to get out and wiggle the controller and hope it will cycle now (Sometimes it works and sometimes I have to do that a few times)
Glow plug problem?
- Thread starter S-west
- Start date
stumiister
Diesel Truck Tech
It sounds like a bad connection on the controller, but you can put a push button on the GP system and that will eliminate the need to change the GP controller
7.3 man
7.3 idi man
I done that to mine. 
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Last edited:
oregon96psd
Full Access Member
To the original poster, don't half ass it fix it right. You've already located the problem, it does sound like a bad connection there, take a look at it. Check all the terminal's in the plug and in the rest of the harness.
7.3 man
7.3 idi man
I'd think you wouldnt want the GP'S coming on when you start the truck every single time.
icanfixall
Official GMM hand model
Please fix whats wrong and not rewire a perfectly good working system. Fix the problem.. Be careful with the always hot power line too. Now lots of times the main engine wire harness plug gets some corrosion in it. Then it melts and sometimes starts a electrical fire.. Then you are screwed big time. So open up that retangle plug on the passenger side of the engine. Kill the batteires too so there wont be any flash over. Post back if you find a problem. Also one more thing. Once the coolant system reaches 120 degrees the fast idle, the internal advance and the glow plugs wont work any more till the coolant temps drops to less than 120 degree. You hard starts is from something other than the glow plugs no matter what wire you wiggle to make it start.
7.3 man
7.3 idi man
I bought two controllers for mine and both were bad so I wired mine over to manual system, even new controllers would activate when the engine is hot, good temp sensor.
What would cause the hard start then? I'm not losing prime because when the glow plugs do finally cycle it starts fine. And The compression in every cylinder is between 420 and 450. Could it posibly be an injection pump going? When it doesn't start it turns over fine and white smoke comes out of the exhaust but it doesn't fire at all.
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