LMTV (M1079) STOPS RUNNING WHILE DRIVING

[jedatide]

I have a 2004 M1079, that I purchased some time back. While driving the vehicle it will eventually stop running/shut off. I drive it, maybe 15 miles, then it dies. I am assuming it has something to do with the temperature (coolant). I then have to wait 15-20 minutes and it will start right up. However, it will not go as far, before it shuts down again. Then the process repeats itself until I eventually make it back home. I looked through the TM's and I cannot find anything about what would (all the reasons) that will shut the vehicle down. Any assistance/guidance would be greatly appreciated. Thanks.

 

[HDN]

Have you checked anything? Possible air, fuel or exhaust restrictions? Replace or clean any filters lately?


Maybe this thread off-site would be of help:

3126 cat shuts off while driveing

www.thedieselgarage.com

This fellow had a similar problem and it turns out it was mainly a problem with a bad muffler.

 

[FarmingSmallKubota]

I have a 2004 M1079, that I purchased some time back. While driving the vehicle it will eventually stop running/shut off. I drive it, maybe 15 miles, then it dies. I am assuming it has something to do with the temperature (coolant). I then have to wait 15-20 minutes and it will start right up. However, it will not go as far, before it shuts down again. Then the process repeats itself until I eventually make it back home. I looked through the TM's and I cannot find anything about what would (all the reasons) that will shut the vehicle down. Any assistance/guidance would be greatly appreciated. Thanks.

Some important information to look at do you have a 3126 or a C7, are your batteries good, good grounds, air leak in the fuel system. not giving us much to go on. This would also be better in the LMTV forum

 

[jedatide]

Have you checked anything? Possible air, fuel or exhaust restrictions? Replace or clean any filters lately?


Maybe this thread off-site would be of help:

3126 cat shuts off while driveing

www.thedieselgarage.com

This fellow had a similar problem and it turns out it was mainly a problem with a bad muffler.

I appreciate the video (I watched it). My situation is that the vehicle runs fine for about 15 miles/20 minutes, and then it shuts itself off. I can wait a little time and it will start up and run again. The longer I let it sit, the longer it will run, until it shuts off. I believe it has something to do with it getting hot (engine, transmission, etc.). But, I do not know what all is programmed to shut the vehicle off, before causing significant damage to the vehicle.

No, I have not checked anything yet. Honestly, really did not know where to start. Looking for advice to hopefully point me in the right direction with minimal time, effort and cost. I did not know if the TM's had a diagnostic section for this problem. To identify, or list, all the things that would make the vehicle shut off while driving.

 

[Lostchain]

Could even be bad wiring to the ECM, my understanding of the CAT programming is that it will derate the power but not actually shut off the engine from an overheat. Bottom line, you need a scan tool hooked to your truck while driving to continue diagnosis. Otherwise you are pissing in the wind.

 

[Mogman]

Moved to a more appropriate forum

 

[TNDRIVER]

I appreciate the video (I watched it). My situation is that the vehicle runs fine for about 15 miles/20 minutes, and then it shuts itself off. I can wait a little time and it will start up and run again. The longer I let it sit, the longer it will run, until it shuts off. I believe it has something to do with it getting hot (engine, transmission, etc.). But, I do not know what all is programmed to shut the vehicle off, before causing significant damage to the vehicle.

No, I have not checked anything yet. Honestly, really did not know where to start. Looking for advice to hopefully point me in the right direction with minimal time, effort and cost. I did not know if the TM's had a diagnostic section for this problem. To identify, or list, all the things that would make the vehicle shut off while driving.

First thing I would do is put an eyeball in the fuel tank an see if something is floating around in the fuel.........i9f not start changing the filters..... my 2 cents...

 

[MatthewWBailey]

I appreciate the video (I watched it). My situation is that the vehicle runs fine for about 15 miles/20 minutes, and then it shuts itself off. I can wait a little time and it will start up and run again. The longer I let it sit, the longer it will run, until it shuts off. I believe it has something to do with it getting hot (engine, transmission, etc.). But, I do not know what all is programmed to shut the vehicle off, before causing significant damage to the vehicle.

No, I have not checked anything yet. Honestly, really did not know where to start. Looking for advice to hopefully point me in the right direction with minimal time, effort and cost. I did not know if the TM's had a diagnostic section for this problem. To identify, or list, all the things that would make the vehicle shut off while driving.

Does the dash go blank when it shuts down? If not, are there any indicators?

I know for a fact that a brownout will shut the engine hard. My 2 cents is that you're operating on battery only, ie no consistent alt power. With 4 batts, you could run awhile until 24v bus drops below 16. Then it rebounds when you're off. Just my theory

 

[GeneralDisorder]

You need a J1939 scan tool, or a laptop with CAT ET. As @Lostchain said - you are just spinning your wheels and wasting diagnostic time till you talk to the computer (or not if it's the problem) and look at live data.

3126b or C7 truck?

The 3126b had a deprecated EMI/RFI filter box on the power feed to the ECM - it's mounted on a bracket just outboard of the ECM on the engine block. Those were supposed to be bypassed but the bypass cable can fail (or it was never bypassed and has failed) at the connectors where water gets in and causes corrosion inside the back of the connectors where they are soldered.

 

[Ronmar]

Yep, what are the gauges doing, particularly the volt meter.

you may be right, something is getting warm, perhaps the circuit board in the ECU…

if nothing happens on the dash and it is making 28V on the meter and drops to 24-26(batt voltage), hop out and immediately open the fuel cap. Does it suck air.. these things move/recirc a lot of fuel but if the vent were clogged the tank pulling a Vacume could effect the lift pumps ability to pull fuel.

 

[Lostchain]

1st two things to check from the 3126 book are wiring related

 

[aw113sgte]

How about a clogged tank vent? Runs until tank vacuum is too high, then shuts off, slowly vacuum decreases and allows a restart. Take fuel cap off and blow into vent hose to check.

 

[Skyhawk13205]

What are the symptoms of the shutdown? Does the truck shut off as if you shut down the master switch?

Does the electrical power stay on after the shut down?

You need to narrow down your problem to an electrical, mechanical, hydraulic problem or a combination of the three.

Typical hot coolant will give a derate, you would see the check engine light flash and a reduction in power.

 

[hike]

The 3126b had a deprecated EMI/RFI filter box on the power feed to the ECM - it's mounted on a bracket just outboard of the ECM on the engine block. Those were supposed to be bypassed but the bypass cable can fail (or it was never bypassed and has failed) at the connectors where water gets in and causes corrosion inside the back of the connectors where they are soldered.

Is this the deprecated EMI/RFI filter box? It was at the rear of our ECM when we pulled to send to you. It wasn't connected to anything at the time, just hanging out—

 

[Lostchain]

Is this the deprecated EMI/RFI filter box? It was at the rear of our ECM when we pulled to send to you. It wasn't connected to anything at the time, just hanging out—

View attachment 926015

Yes that is it. You will have a special jumper to connect the cable ends that used to go into that box. The power for the ECM goes through that and problems with the box or wiring could cause the “engine switch off” symptoms the OP describes. As it is bolted directly to the engine, depending on the failure mode there could also be the nexus to engine temp the OP observes.

 

[GeneralDisorder]

Is this the deprecated EMI/RFI filter box? It was at the rear of our ECM when we pulled to send to you. It wasn't connected to anything at the time, just hanging out—

View attachment 926015

Yep. That little guy is discontinued and apparently unnecessary. But our tax dollars bought one for every truck because reasons...... 2000 of them per truck if you count $'s as reasons. Been meaning to open one up and see what cost so damn much money.

 

[jedatide]

Yep, what are the gauges doing, particularly the volt meter.

you may be right, something is getting warm, perhaps the circuit board in the ECU…

if nothing happens on the dash and it is making 28V on the meter and drops to 24-26(batt voltage), hop out and immediately open the fuel cap. Does it suck air.. these things move/recirc a lot of fuel but if the vent were clogged the tank pulling a Vacume could effect the lift pumps ability to pull fuel.

Wow! I really appreciate all the assistance. When I get a chance, I believe I will start with checking the vacuum on the fuel tank. Unfortunately, life happens, and I have not had time to work on it. I will eventually get to it. You fellas have provided enough information to help me to trace down the problem. Thanks again, for all the help.

 

[MatthewWBailey]

Yep. That little guy is discontinued and apparently unnecessary. But our tax dollars bought one for every truck because reasons...... 2000 of them per truck if you count $'s as reasons. Been meaning to open one up and see what cost so damn much money.

Was that supplied on all trucks? I didn't see that when I pulled my ECM.

 

[GeneralDisorder]

Was that supplied on all trucks? I didn't see that when I pulled my ECM.

AFAIK it was on all the 3126b trucks - at least through @Lostchain 's 2003 and the C7 came along in 2004.5...... The C7's don't have it so it would seem to have been done-away-with around that time frame. The 3126b and C7 use near identical ECM's. I think it was a precaution that turned out to be unnecessary.

 

[MatthewWBailey]

AFAIK it was on all the 3126b trucks - at least through @Lostchain 's 2003 and the C7 came along in 2004.5...... The C7's don't have it so it would seem to have been done-away-with around that time frame. The 3126b and C7 use near identical ECM's. I think it was a precaution that turned out to be unnecessary.

I've reconfirmed. I do not have that device on the engine. '04 year