24 volt to 12 volt "module"

[landstew]

Hey all. I've been searching the threads and can't find this one exactly. I don't really do electrical so took my m1009 to a shop to diagnose my intermittent glow plug system. Sometimes will not get a wait light and will not start. Sometimes will and it starts and runs beautifully. Happens sometimes hot (left me stranded) and sometimes cold after previously working a few days fine. Tested the solenoid (blue wire ground) , its clicking. My card doesn't "look" fried, never smelled anything. And it's been an intermittent problem anyway.

Anyway, yesterday the shop called me and said they traced it to "12 volt wires where there should be 24, and it's caused the module that steps down the 24 volt to 12 to be burned out. I know a guy who works on computers and he can fix it." I didn't know what he was talking about and don't even want to tell the number he said to fix it. I told him from what I understand the 24 is brought down to 12 by the resistor bank on the firewall and he stutters and says he'll have to talk to his techs and get back to me. I asked him to send me a photo, and still nothing yet. So... what is this guy talking about? Does any of that make sense? This is only an intermittent problem.

 

[landstew]

By the way, he also said that it is effecting the fuel pump as well. I asked if he means injection pump and he said well another fuel pump on or by the injection pump. Again I am not sure what he means. Thought this just has an injection pump. I was able to start it with starting fluid before (I know not recommended, just was a test), and it ran fine after that, so I don't know how what he's saying could be possible. Anyway I think you all know where I'm going with this, but before I pull it out of there just checking if any of this rings true at all. Thanks!

 

[Recovry4x4]

Go get your truck! This dude might be crazy. We can walk you through your GP issues but DO NOT leave it at the shop where it's at. Also, don't use that starting fluid at all, but in extreme emergencies, after the glowplugs are unplugged.

 

[Curtisje]

Yup. I agree with Recovery4x4. Get your truck out of there before any damage is done.

 

[MarcusOReallyus]

I'll third the motion. DO NOT LET THOSE IDIOTS TOUCH YOUR TRUCK!!

They have no idea what they are talking about.

Get it home and we'll get you going.

 

[MarcusOReallyus]

By the way, he also said that it is effecting the fuel pump as well. I asked if he means injection pump and he said well another fuel pump on or by the injection pump. Again I am not sure what he means.

That's because HE is not sure what he means. Actually, he has no idea what he means. I mean, NONE.

Thought this just has an injection pump.

No, you also have a lift pump that pulls the fuel from the tank and sends it up to the injection pump. It's mechanical. Old school mechanical fuel pump mounted to the engine block. You've probably seen plenty of them on gasser engines. No 12 volts, no 24 volts. No electrical connections at all.

Does that tell you how little this clown knows?

 

[Curtisje]

 

[nyoffroad]

Go get your truck! This dude might be crazy. We can walk you through your GP issues but DO NOT leave it at the shop where it's at. Also, don't use that starting fluid at all, but in extreme emergencies, after the glowplugs are unplugged.

All this^^ but i'd like to add one small thing, if you insist on using starting fluid don't just unplug the glow plugs make sure that they have cooled down!

 

[landstew]

Thanks everyone. I got the truck back a couple days ago. It was a surreal story. There was a period of 36 hours the guy wasn't calling me back and I didn't know where it was. Suddenly got this call from someone saying they had my truck and if I'm going to pick it up. I said of course and ...who the hell are you. The guy I was originally dealing with farmed it out to them without telling me, no permission, estimate or anything. I had 3 people on the phone try to explain what they did, (there were some translation issues too) as it still didn't make sense. Soldering a transformer by the batteries, connect some relay under the dash better blah blah. I smelled bunk and went over right away, far side of town. When I got there, I did see a bunch of diesel trucks being worked on so it was a diesel place at least. Walked over to mine tried it, Wait light came on and its firing right up. But I told them I still don't know what they did, and I think it's illegal to work on a car without me authorizing anything. They said the owner who worked on it wasn't there so they didn't know either. But they can't let it go without payment. I just wanted it back and to be done with this so I talked them down to a few hundred and drove it out asap. I feel ridiculous paying them anything but hey it has been firing up the past few days, running great. I just feel no one wants to follow any laws in this town as I have right to know what, if anything, was worked on, and by whom.

 

[Keith_J]

Wow. Lesson learned at a high price. I would recommend downloading the technical manuals and learning how these vehicles work. It isn't difficult, all the help needed is here. If you cannot find it with a search, ask away. We are mostly friendly and will get you on the right path.

 

[Curtisje]

Thanks everyone. I got the truck back a couple days ago. It was a surreal story. There was a period of 36 hours the guy wasn't calling me back and I didn't know where it was. Suddenly got this call from someone saying they had my truck and if I'm going to pick it up. I said of course and ...who the hell are you. The guy I was originally dealing with farmed it out to them without telling me, no permission, estimate or anything. I had 3 people on the phone try to explain what they did, (there were some translation issues too) as it still didn't make sense. Soldering a transformer by the batteries, connect some relay under the dash better blah blah. I smelled bunk and went over right away, far side of town. When I got there, I did see a bunch of diesel trucks being worked on so it was a diesel place at least. Walked over to mine tried it, Wait light came on and its firing right up. But I told them I still don't know what they did, and I think it's illegal to work on a car without me authorizing anything. They said the owner who worked on it wasn't there so they didn't know either. But they can't let it go without payment. I just wanted it back and to be done with this so I talked them down to a few hundred and drove it out asap. I feel ridiculous paying them anything but hey it has been firing up the past few days, running great. I just feel no one wants to follow any laws in this town as I have right to know what, if anything, was worked on, and by whom.

What town is that?

Glad you got your truck back AND its running. Time to figure out what they did as it's likely to fail in the long run.

 

[MarcusOReallyus]

Glad you got your truck back AND its running. Time to figure out what they did as it's likely to fail in the long run.

Exactly right. There's no telling what kind of hack job they did. From what you said, it does not sound good. Don't be fooled by the fact that it runs now. What happens when it fails? Who's going to work on it then? The same shop? You'd have to be pretty stupid to go back there again!

I suggest you start by filing a complaint with whatever state agency regulates mechanics where you live. Might not do any good, but at least it will be on record. Then (with our help) restore the truck to its correct (stock) operating configuration, and keep track of every penny it costs you. Then file a small claims action to get your money back. ALL of it, including what they extorted out of you.


Even if you don't want to go the legal route with them, I still suggest you put it back to stock. Post pictures of the wiring, especially anything they added, and we can help you sort it out.

 

[landstew]

Now I actually don't think they did anything. Which is good (and bad of course.) Good for the truck.

Yep, the problem came up again. It's intermittent. I've tested the relay. It's working. (Clicked when I grounded it from the light blue wire to the block and turned the key.) Does that mean it's the card? Again, everything will work fine sometimes. Then other times not, whether I try it in the morning; or just drove it an hour before, when it had suddenly worked fine again before that. (This is the worst scenario as it's left me stranded.)

 

[jeffhuey1n]

Did you do the doghead mod? I had similar problems. I looked through a bunch of posts to discover potential fixes. I replaced all the glow plugs, which were shot. I also did the relay mod and then got rid of the original fuel filter. I put a spin on filter mount in it’s place and haven’t had a starting problem since. I even had the truck sitting for a couple years while working on other projects and it still started right up, after I changed the batteries.

 

[Barrman]

There are 3 main parts that have to work together for the glow plugs to function. The temperature sensor in the drivers side head at the rear, the glow plug relay and the glow plug card. Plus all the wires in between, the glow plugs themselves, both batteries load tested at full strength, the ignition switch, etc...

The troubleshooting section of the -20 manual is your best bet for tracing the problem. Follow it step by step by step. Starting with getting the batteries load tested. That really does matter.

You have mentioned the glow plug card and the glow plug relay. Next time it does nothing, jump out and wiggle the plug on top of the temperature sensor. I had a sensor on one of my M1009's that had an internal fault in it. Just putting my hand on the plug would cause the system to work. The relay would click as soon as I touched it. Of course, there were two different versions of this sensor with different plugs on them. The original or older version is no longer available.

Follow the -20. But, try the sensor plug if you get stuck somewhere in the mean time.

 

[Sharecropper]

The original or older version is no longer available.

Follow the -20. But, try the sensor plug if you get stuck somewhere in the mean time.

The GM part number for the original glow plug temperature sensor is 10045847. Occasionally a NOS unit will pop up on Ebay. You might want to do a search on there and see what happens.

 

[MarcusOReallyus]

Starting with getting the batteries load tested. That really does matter.

Yep, yep, and yep.

And clean your connections. ALL of them. Especially the grounds.

 

[Tinstar]

Please post the shop name and town it’s in.
Do not mention that mechanics name here.

It will help others in the future in avoiding that shop.
Also file a complaint with the Better Business Bureau.

Yes
They were not supposed to hand your truck over to another shop without your permission.
Verbal or written
Each State will have different laws about this.

It’s usually not worth the time and lawyer expense to take it to court.
That part is entirely up to you.
Now if your truck was stolen or damaged/destroyed while at the other shop then you would have a good case.

At least you have your truck back.
Lesson learned.
Like already mentioned, the guys here can and will help get it back to stock.

Once you understand how the system works it’s easy.
Buy the best parts you can afford.
When properly maintained, the stock CUCV is a very reliable vehicle.

 

[Sharecropper]

The GM part number for the original glow plug temperature sensor is 10045847. Occasionally a NOS unit will pop up on Ebay. You might want to do a search on there and see what happens.

I'll be dang. Looking through my spare parts bin I happen to have a couple of those NOS AC Delco glow plug temperature sensors.

 

[Bigdawgpeat]

There are 3 main parts that have to work together for the glow plugs to function. The temperature sensor in the drivers side head at the rear, the glow plug relay and the glow plug card. Plus all the wires in between, the glow plugs themselves, both batteries load tested at full strength, the ignition switch, etc...

The troubleshooting section of the -20 manual is your best bet for tracing the problem. Follow it step by step by step. Starting with getting the batteries load tested. That really does matter.

You have mentioned the glow plug card and the glow plug relay. Next time it does nothing, jump out and wiggle the plug on top of the temperature sensor. I had a sensor on one of my M1009's that had an internal fault in it. Just putting my hand on the plug would cause the system to work. The relay would click as soon as I touched it. Of course, there were two different versions of this sensor with different plugs on them. The original or older version is no longer available.

Follow the -20. But, try the sensor plug if you get stuck somewhere in the mean time.

Where can i find a glow plug card ?