Possible glow plug problem

[Riverhawk]

I've had my M1009 for less than a year now so I still have a lot to learn. Some time last fall when I attempted to start the engine the wait light remained on. Usually it goes off in about 15 seconds. Eventually it started; I don't remember if the light went off or not before starting. After a trouble free winter I had the same experience this morning. I let it go for about 30 seconds, two times, and then tried to start it. It did fire up with difficulty, and the light then went off in a few seconds. I drove to work and it's sat there all day. I just started it after glowing for about 25 seconds, again with difficulty, however the light did go off. What am I looking at here? I'm sure this is not my unique problem. Any help would be appreciated.

 

[howardc]

How new are the batteries? Does it crank fine or sluggish?


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[tim292stro]

Is the Glow Plug relay clicking when you turn the key to On? Do you have a 12V mod on the glow plug circuit? What was the measured voltage on the fat orange wire terminal of the GP relay under the hood while the key is turned on?

Glow plugs are a maintenance item, they need to be checked twice a year - and if one goes bad, the best advice I can give is to replace a matched set of 8 at the same age.

 

[Riverhawk]

Thanks for the input. Batteries are fine and it cranks as it should. I'll get under the hood and check out your suggestions. Where is the glow plug relay located? I see a small round one at the upper left of the brake master cylinder that appears to be it. Correct? The vehicle has been converted to all 12 volt. I went out this morning at 30º and the wait light remained on for over a minute. Cranking did not start the motor. After quite a few cranks it coughed several time but wouldn't catch. During cranking the wait light re-appeared as well. At least I got it home last night! I'll use alternative transportation today and hope to get into it sometime this weekend. Would the light remain on if it's a glow plug issue? I did hear a relay click about 30 seconds into the glow time but the light stayed on. I'm suspicious that they are not getting any voltage to make them operate. One hour later, I just went out and tried it again. I opened the hood to hear better, turned the key and heard the relay click. I went around to the front, (key is on), and waited 'till I heard the second click I mentioned before, (louder than the first), returned to the cab and the light was out. Turned the key to start and it fired instantly. Whatever I've got it appears intermittent. It's the story of my life I fear.

 

[cucvrus]

Glow plugs are a maintenance item, they need to be checked twice a year - and if one goes bad, the best advice I can give is to replace a matched set of 8 at the same age.

I have never had any problems with just changing the bad glow plug. On occasion I have replaced all 8 with new AC Delco 13G but only when I am asked to do so by a customer. I keep the old ones and then test them and discard the bad ones and use the good ones as needed. I just never opened up the hood and removed them and discarded them as a maintenance item. I have a few trucks that I have not had the glow plugs out of in 5 years. They get run daily and fire right up. I am not sure I would check them or change anything on the glow plug system on a semi annual basis.
Last time I had any glow plug problem I had the wait light coming on in the middle of the day or anytime I hit a bump. It turned out to be the ground cable on the front battery being loose. Have a great day. And anytime you have to change your glow plugs semi annually you have other problems. end me your old glow plugs that you are changing out. I will put them to good use. But if they are not AC Delco 13 G you can toss them. I used old glow plugs for fishing sinkers.

 

[Tinstar]

If you have had the truck for almost a year and still don't know exactly where the GP relay is, I would suggest a dive into the TMs.

I don't know everything about these trucks and don't even pretend to, but I do know what and where the basic parts in the electrical system are. Etc
Warthog has posted excellent color coded schematics that really help in traceing circuits.

I had lots of issues when bringing my M1008 back to life
With the old threads and TMs and the search feature, I only had to ask here as a last resort.

If you can't raise the hood and name every part and its function then continue reading.
I'm still doing this with my 5 tons and the air system. It's a complex air system and crawling underneath with a TM to figure out what things do isn't fun, but it needs to be done.

This isn't intended to start anything nor is there a sharp tone with it.

The more you know the better. Especially if you have to troubleshoot or fix something in the middle of nowhere.

 

[Riverhawk]

Thanks, folks. After viewing another more recent thread with the same problem I got a new relay and all is right with the world, or at least with the glow plugs. I understand what you're saying, Tinstar. However there are a lot of things to learn, and if a post here gets me going in the right direction I call it a victory. I appreciate all the advise. Maybe someday I'll be able to return the favor.

 

[Tinstar]

Thanks, folks. After viewing another more recent thread with the same problem I got a new relay and all is right with the world, or at least with the glow plugs. I understand what you're saying, Tinstar. However there are a lot of things to learn, and if a post here gets me going in the right direction I call it a victory. I appreciate all the advise. Maybe someday I'll be able to return the favor.

The post wasn't for the troubleshooting, but for the basics.
If you know what is what and it does this and that.

Then when you post about an issue, you know what to look for/at when someone says to check a part, etc.

Glad you have fixed that particular issue.

 

[Riverhawk]

Thanks! I appreciate the advise.