CUCV glow plug solenoid dance

[northseacat]

Glow plugs were operating correctly. Last week on start-up glow plugs cycled normally...for a short time. then the cycling started racing on-off-on-off. I shut the ignition off to stop it. Something new to me...any ideas?

 

[Zenk]

I had the same thing happen to my M1028. Very rapid GP relay cycling on and off (like a machine gun). It is random on my truck. I usually pull the GP Controller card from under the dash and clean the contacts and that seems to fix it. Could be a coincidence but that is what I did. Maybe we need new cards or GP card bypass. I also have random no GP dash light.

FYI... I have new GP Relay... Doghead Starter Relay Mod... New Glow plugs (Bosch)... resister bypass.

 

[FMJ]

I've experienced the same issue, replaced gp controller card no effect.

 

[Gripy]

Are your gp, s switched to 12v or are they still 24v. If still 24v then it is a sign that you have burnt out gp's. Gp controller cycles to keep the gps from burning out too quickly.

 

[Zenk]

Are your gp, s switched to 12v or are they still 24v. If still 24v then it is a sign that you have burnt out gp's. Gp controller cycles to keep the gps from burning out too quickly.

Glow plugs are 12v from the factory... and they are still 12v. CUCVs never came with 24v glow plugs. The resister took the 24v input and stepped the voltage down to 12v (assuming all GPs are working). When you do the resister bypass, you wire the GP solenoid to a 12v source.

 

[AECS]

I would say you have a ground issue. That or the card. Ground is cheaper try that first.

 

[southdave]

mine did that, til i notice a bear wire on the coolant temp sender, got rubb at some point

 

[M1008driver]

"Glow plugs were operating correctly." I suspect this is not true. My M1008 did the same thing. First I thought fuel and changed the filter only to be disappointed. I changed all 8 glow plugs and the problem was solved. That's my experince with a racing engine after start. The fuel did not heat up enough even in the summer.

 

[MarcusOReallyus]

Glow plugs are 12v from the factory... and they are still 12v. CUCVs never came with 24v glow plugs. The resister took the 24v input and stepped the voltage down to 12v (assuming all GPs are working). When you do the resister bypass, you wire the GP solenoid to a 12v source.

I think that's what he meant. If you are still running with the stock system, and a GP or two fails, the remainder of the GPs will see higher than 12v. This will confuse the GP card, and shorten the life of the GP.