I thought my GPs were working properly, now I dont know...

[Corvette1974]

Alright, so I have an 86 M1028. It has fresh GP relay, and all new GP's. It starts fine no matter what. One thing though- I watched this video [media]http://www.youtube.com/watch?v=MTkOl947aTk&feature=youtu.be[/media]

and this is NOT how my system operates.


Heres how mine does-

Cold start:

Turn key, light on for like 15 seconds, this whole time I can hear the GP relay cycling on and off and watch the voltage increase/decrease accordingly. It does NOT seem to just leave the GP's on, it cycles them even on a dead cold start. Light off, turn key and starts, then after glows.

Heres the thing- On a hot start: Turn key, light on and a FULL cold cycle starts - the whole cycle on and off for 15 seconds occurs, even though the engine is at operating temperature.

So two problems, or at least according to the video, It doesnt just keep the GP's on during a cold start, and during a hot start, it treats it as a cold start.

What is the deal here? Is a new GP card in my future?

Will

 

[doghead]

There is a very easy to follow(and thorough) troubleshooting guide in the -20 TM.

 

[Corvette1974]

There is a very easy to follow(and thorough) troubleshooting guide in the -20 TM.

Hahaha I know everything is in the TM's, and I read them frequently. Im not even home to see the truck, I'm just wondering if anyone's like "oh yeah I know that problem it is this, this and this..." I'll check it out...

Thanks,
Will

 

[doghead]

It sound's like your glow plug temp sensor could be bad.

There's a random(but logical) guess.

I would rather diagnose the system in a methodical manor.

 

[Corvette1974]

It sound's like your glow plug temp sensor could be bad.

There's a random(but logical) guess.

I would rather diagnose the system in a methodical manor.

Hahaha yeah youre right it is probably that....and I agree ill look into it this weekend. Im not gonna lie I just checked out the TM and couldnt find it....brain fart. Do you know where it is in the TM?

Will

 

[doghead]

Which series of TM do you use? the 209 or 361?

 

[Corvette1974]

I found this CUCV Glow Plug System Troubleshooting - CUCV Electric

 

[Corvette1974]

And I use these Tm's http://www.steelsoldiers.com/cucv-tms/77609-tms-cucv.html like the ones supplied by SS

 

[doghead]

The CUCV Electric info is right out of the TMs. Use the TMs for step by step instructions on how to diagnose the GPs.



That list is the 289 series of Tms.

The troublshooting section in the -20 is where you need to look.

When I say -20, I mean the TM number ends with -20.

 

[Corvette1974]

The CUCV Electric info is right out of the TMs. Use the TMs for step by step instructions on how to diagnose the GPs.



That list is the 289 series of Tms.

The troublshooting section in the -20 is where you need to look.

When I say -20, I mean the TM number ends with -20.

Alright sweet sounds good. I'll check em out. And yeah I know the -20 is the -20 one lol

Thanks,
Will

 

[Corvette1974]

Alright- I know that CUCV Electric has the temp sensor, but off hand does anyone know if it is available through a parts store like NAPA or Autozone? Like what is the make and part number in case I do have to replace it?

Will

 

[doghead]

The -20P lists the part number. The manufacturer is AC Delco.

Find that number in the TM, and search the site(or for glow plug temperature sensor). I bet you find dozens of threads with more info.

BTW, did you test your and find it was bad?

 

[Corvette1974]

The -20P lists the part number. The manufacturer is AC Delco.

Find that number in the TM, and search the site(or for glow plug temperature sensor). I bet you find dozens of threads with more info.

BTW, did you test your and find it was bad?

Do you think that the parts stores will carry an AC Delco part or will I have to go to the dealer?

And not yet, still not home from school. Im checking it tomorrow.

Thanks,
Will

 

[doghead]

Yes, parts stores sell AC Delco parts.

 

[Corvette1974]

Yes, parts stores sell AC Delco parts.

Well I know that but I mean a possibly outdated part. Either way, I like driving so I'll get it done. Checking the -20P now.

Thanks,
Will

 

[Corvette1974]

Alright I found it in the TM

The GM number is
10045847

Which is still available and also cross references to WT3000

Autozone has them for $18. Sounds good to me, now I just need to break out the Fluke and test some circuits lol

 

[Corvette1974]

Ok so old sensor out and new sensor in. It seemed to fix the problem! With the engine partially warm the sensor read 40k Ohms- so basically open. I replaced it and cycled the plugs and with a semi warm motor they only cycled for about 8 seconds instead of the 15 that it used to ALWAYS do. I havent started to drive it so I'll get back on the "final" results.

Will

 

[Corvette1974]

Temp sensor did the trick. It is like a new Duramax now! Literally once you do a single cold start normal cycle, the wait light doesnt even come on any more if the engine is remotely hot. It's good to go, works perfectly.

Thanks,
Will

 

[doghead]

Great! Thanks for the update.