Symptoms of bad Glow Plug Card?

[Jack Lope]

While driving, after the truck should already be warmed up, the glow plug relay will click on for a few seconds, then click off. Sometimes it will click on/off repeatedly very rapidly with the voltmeter needle bouncing all over the place. I see the voltmeter dropping about 12v's which is what it normally does when glow plugs are lit. The glow plug relay looks fairly new, but I haven't replaced it since owning the truck. I'm wondering if this is a sign of the glow plug card going out. It's been doing this for a while, but seems to have gradually gotten worse. This sound familiar to any one?

 

[tim292stro]

Doesn't sound right - can you pull out a multimeter and check the voltage?

 

[cpf240]

Maybe the card is doing an after-glow cycle? Perhaps the temp sensor is bad, making the card think the engine is still cold?

 

[Jack Lope]

Maybe the card is doing an after-glow cycle? Perhaps the temp sensor is bad, making the card think the engine is still cold?

Hmm! This is interesting! I'll check with NAPA and find out how much one of those are. It seems I'm going to have to start replacing something.

 

[cpf240]

Hmm! This is interesting! I'll check with NAPA and find out how much one of those are. It seems I'm going to have to start replacing something.

The glow plug system trouble-shooting guide in the -20 TM might help narrow down the problem, before having to buy parts...

 

[Jack Lope]

I was getting out of the truck just now and noticed a little new (as in wasn't there before) blue something on the floor. Picked it up and it was a cap! Pulled the card and there's an empty spot for it. The cap looks in good shape so if I can determine which side is (+) as indicated on the board, I'll solder it back in.

 

[Jack Lope]

Dr. Frankenstein would be proud! Now to go plug it back in and see if it works/fixes my problem. In the pic, it looks like the bottom post might be shorted to the other trace, but it's not.

 

[PJL]

Good catch! The black stripe with the arrow pointing down is the negative lead. Just like the other one that's still attached. And by the way electrolytic capacitor failure is very common in all electronic devices. If you see one that has swelled or leaking fluid it's gone bad. I was given a nice flat panel TV not long ago. Wouldn't turn on. Took it apart and found one bad cap on the power supply board. Couple bucks later and I got a working TV.

 

[tim292stro]

Indeed, electrolytics have approximately a 10 year design life. Wonder why electrical problems are common with ECU type vehicles?

 

[MarcusOReallyus]

And by the way electrolytic capacitor failure is very common in all electronic devices. If you see one that has swelled or leaking fluid it's gone bad..

And even if it's not swelled or leaking or has any other obvious signs, it could still be bad.

 

[gator6romeo]

Hey Jack Lope, what was the outcome of your problem? What fixed it? I am having the exact same problem with my M1008 and need to get it fixed. Thanks man!

 

[Jack Lope]

When I soldered that capacitor back on, it did fix my problem. Maybe check to see if you have a lose capacitor.

 

[MarcusOReallyus]

Lose rhymes with booze.

Loose rhymes with goose.

Since you found your capacitor on the floor, you didn't lose it, but it was loose, so you soldered it.