Glowplug system questions

[Lothar]

I have been replacing wiring and cleaning up a newly acquired M1008. The glowplug system was not operating correctly when I bought the truck. I can tell it was once a well loved truck before a more recent, less talented owner took over and began "fixing" problems. I recently completed replacing all the wiring I found to be spliced up, melted, or otherwise unserviceable. Also replaced the GP relay, glowplugs and temp sensor.
I verified the resistors are working and correct voltage is reaching the new glowplugs when key is turned on. Turning key on, the wait light turns on but only 1 or 2 seconds. The truck fires up and idles but the wait light then will begin turning on and off with a noticeable draw (observed by battery charging meter and audible cycling of GP relay) on the system when the light is off.
This does not quit cycling once truck is warmed up.

I assumed this is a faulty GP card and ordered a new card from hillbilly wizard. My question or questions are, am I on track and is there another possibility that I am not even considering (like improperly wired card)? I appreciate any advice here. This truck is to be the first step in building my new, home based small business and it is taking longer than I anticipated to bring it up to a reliable condition.
Probably unnecessary but I know pics are everything so I will just dump a few before and after here.

 

[WWRD99]

Truck looks great! I have question as to which temp sensor you replaced? If I remember right the one the triggers the glow plugs is on the rear of the drivers head. They came out with a new style one with a 2 prong gm plug and sensor. The original one is a single wire. Did you install the new card yet? I see you have the glow plug resistor hooked up still does it drop the voltage to the relay to 12 volts still? Some of those burn up and let more volts through.

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[Lothar]

Thanks for responding. I am waiting for the card to be delivered. The sensor was replaced with the original 1 wire Borg Warner sensor.

 

[WWRD99]

Ok was it on the drivers back head? It could be the card though!

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[Lothar]

Ok was it on the drivers back head? It could be the card though!

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Yes sir, that's the one. I am just a bit reluctant to simply plug a new card in. Hope it would solve everything but with the way things have been going lately, it seems like if I do that the new card will be damaged and I will still be lost.

 

[WWRD99]

I hear that completely!! I've got several spare ones that work but very old. I'd be upset if a new one got damaged! I'd check the resistor output and make sure it's at the 12 volts. I think the small wire that hooks up with the glow plug output goes to the card so over volts would be bad. I'd have to look at the wiring diagram to be sure 100% though.

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[Lothar]

I hear that completely!! I've got several spare ones that work but very old. I'd be upset if a new one got damaged! I'd check the resistor output and make sure it's at the 12 volts. I think the small wire that hooks up with the glow plug output goes to the card so over volts would be bad. I'd have to look at the wiring diagram to be sure 100% though.

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The resistor is functioning properly.

 

[Lothar]

While cleaning up the card and connections, I found a couple leaky capacitors and ordered replacements from amazon. 9 bucks for 4 of them so it's worth a shot. Especially since they will beat the new card here.

 

[Lothar]

The new capacitors didn't help at all. But the new card was the solution.