2008 LTMV goes into over charge dash shuts off

[GeneralDisorder]

How do you access the top of the grounding strap? It seems to be behind the body mount. I ohm'd the strap it did ok there. I have a new issue with the light cluster thinking it is knight rider. The lights are going back and forth.

Ohm test won't tell you anything. Never use that unless you are actually testing a resistive device or circuit such as an incandescent light bulb, a relay coil, or an actual resistor. Ohm setting on your meter is COMPLETELY USELESS for the vast majority of troubleshooting you will do for wiring connection problems. Forget it exists (unless you actually need it).

You need to perform a Voltage Drop Test. Here is one video - there are many more. Do a search and watch videos till it makes sense:

So you have the warning lamp chase sequence going? That means the annunciator panel isn't connected to the MMDC via it's internal CANBUS. That is most probably a power supply issue or low voltage issue, etc. Unless other things have been touched since it worked last?

How long has the truck sat this time? Are you absolutely sure the batteries are good and FULLY CHARGED? Check that FIRST and the battery connections. If you are SURE that is good start by checking all the breakers (or fuses). And then check that you have power at both the input and outputs of the 12v and 24v ignition relays under the PDP. You can access them between the PDP modules if you are careful. They are big relays with big wires and supply 12v and 24v ignition switched power to power up all the ignition switched circuits in the PDP modules.

 

[MGVFD]

Ohm test won't tell you anything. Never use that unless you are actually testing a resistive device or circuit such as an incandescent light bulb, a relay coil, or an actual resistor. Ohm setting on your meter is COMPLETELY USELESS for the vast majority of troubleshooting you will do for wiring connection problems. Forget it exists (unless you actually need it).

You need to perform a Voltage Drop Test. Here is one video - there are many more. Do a search and watch videos till it makes sense:

So you have the warning lamp chase sequence going? That means the annunciator panel isn't connected to the MMDC via it's internal CANBUS. That is most probably a power supply issue or low voltage issue, etc. Unless other things have been touched since it worked last?

How long has the truck sat this time? Are you absolutely sure the batteries are good and FULLY CHARGED? Check that FIRST and the battery connections. If you are SURE that is good start by checking all the breakers (or fuses). And then check that you have power at both the input and outputs of the 12v and 24v ignition relays under the PDP. You can access them between the PDP modules if you are careful. They are big relays with big wires and supply 12v and 24v ignition switched power to power up all the ignition switched circuits in the PDP modules.

Thank you for your quick reply. We are having newer steer tires put on now. I'll see if I can test this when he is finished. Will have some like new 2008 Goodyear tires for sale. Lol Truck has set for about a month. It was clicking and dash lights and gauges were off and on the last time I was here, but the truck started and ran.

 

[MGVFD]

Tested the batteries. Row nearest the frame are reading 12.4v. The out side row are just at 2v. I'll get a charger and charge the batteries up.

 

[GeneralDisorder]

Tested the batteries. Row nearest the frame are reading 12.4v. The out side row are just at 2v. I'll get a charger and charge the batteries up.

Yup. 98% of the problems with these trucks are batteries and battery/ground connections. I honestly can count on one hand the number of trucks I've seen "not start" that wasn't one of those or a *slightly* deeper wiring problem like the 3126b deprecated EMI/RFI box and it's MWO jumper delete harness.

 

[MGVFD]

I'll have to search what the EMI/RFI box is.

 

[MGVFD]

3126 ECU mystery box

Can anyone identify this box to the right of the engine ECU that has two threaded plug connectors with nothing attached to them. This is a 2003 M1078A1 with the 3126B engine. Each plug has two pins in it. The box had been by passed before I picked it up from the air force base. With a short...

www.steelsoldiers.com

found it thanks for the suggestion I'll check to see if I have one in the 2008 A1

 

[GeneralDisorder]

C7 trucks don't have it. It was only used on the 3126B and later deleted. I've only a seen a few trucks that still had them actually connected. Most that have them they are just bolted to their bracket by the ECM and disconnected. Isn't your other truck an older A1? The engine switchover was about 2004.5

 

[MGVFD]

C7 trucks don't have it. It was only used on the 3126B and later deleted. I've only a seen a few trucks that still had them actually connected. Most that have them they are just bolted to their bracket by the ECM and disconnected. Isn't your other truck an older A1? The engine switchover was about 2004.5

Yes it is a 2003. We are getting it ready for paint and ordered the skid unit for the back. I'll check and see if the box is there and if it is connected.