Won an M1083A1 - 1900 mile recovery trip soon! (ND to CA)

[Suprman]

Is the polarity box still bypassed? Both voltages? You can try unplugging the military connector from it. See if you can pull up any codes from the trans keypad. If you have power to the engine electronics you can try to crank from the engine bay switches.

 

[dxhend2]

Thanks suprman, yes, the LBCD is still bypassed, both 12 and 24v sides. Will try unplugging and replacing the military connector. Then retrace our exact steps we did the other day. Be right back.

Sent from my 0PJA2 using Tapatalk

 

[Suprman]

Unplug the connector from it and leave it unplugged.

 

[dxhend2]

It's unplugged, no change. Retracing our exact steps the other day when we bypassed the LBCD.

Sent from my 0PJA2 using Tapatalk

 

[fuzzytoaster]

I'm not saying this is the answer but if signs point to a defunct push button controller I just had one rebuilt for my A1. I could over night it to you to get you home. Let me know, offer stands.

 

[NDT]

Voltage too low!! <- Retract that, voltage is OK with alternator not outputting.

 

[Suprman]

They have wtec5 probably. Unhappy trans can inhibit crank. Bad lbcd can cause improper batter charging. Trans issue will usually have a code on the keypad. If you have power to all electronics with dash switch you can jump the starter. But it may start in gear so be careful.

 

[tennmogger]

Doesn't the latest partial power up and NN on the transmission indicate the transmission is happy again? If there were still transmission faults with power to transmission back on, wouldn't those faults cause a display other than NN? I know that when my transmission went wonky, as Dan mentioned, the transmission would not come back to NN. It would not shift out of the "stuck" transmission gear indicated. BTW, the fault with my WTECII transmission was a disconnected connector from the backside of the keypad (probably not applicable to WTECIII which is different?).

Dan, the failure to power the starter sure sounds like your original problem rearing it's head again. Doesn't it?

Playing devils advocate, what if bypassing the LBCD back in ND was not the real fix. What if the truck just decided to start that one time during the various tests and bypasses you did. No doubt the transmission faulted there in SLC, you had a code, right? but the NN might mean the transmission has cleared it's fault (after power cycle) and now you are looking back at the original problem?

I truly hope this is not the old power problem back again (meaning that bypassing the LBCD was not the cure). but, you don't want to chase a transmission problem that does not exist.

Please, Suprman, others comments?

Bob

 

[Suprman]

The trans can still come up in neutral and have a stored code from a previous incident. If the truck was stuck in a gear Ans speed went up or down out of that gears range, and it didn’t shift then a code as to why should have been stored. The wtec5 module is under the passenger dash. The military got rid of this truck because it has gremlins. Unfortunately the tm dosnt have a troubleshooting section for intermittent problems. Ther could be a loose connection somewhere or a wire rubbing thru against something.

 

[NDT]

How about pull codes on transmission? Press up and down key at the same time and report back.

 

[dxhend2]

P0721
P0880
P2685
P2812
P0974


Sent from my 0PJA2 using Tapatalk

 

[dxhend2]

Still have power to the dash, tried jumping across the starter solenoid with a screwdriver, got an arc but not hing from the starter motor.

Sent from my 0PJA2 using Tapatalk

 

[NDT]

Codes mostly related to voltage issues in TCM. Do you have a way to google the codes? I think the WTEC is inhibiting crank because it feels really sick.

 

[dxhend2]

NDT, that could explain current behavior, googling codes now. Will also look for Allison support here in SLC if we need to go that route.

Sent from my 0PJA2 using Tapatalk

 

[NDT]

P0880

Disappearance of power supply control unit during operation engine P2685 Low voltage in the circuit HSD3 P2812 Open circuit solenoid PCS6 Incl. DNS, SOL OFF ON. DNS, SOL OFF

 

[NDT]

DNS is do not shift (the TCM that is, not you)

 

[NDT]

I would re-seat all the connectors related to the Allison. Behind the dash, the one at the left front of the engine under the cab, and the ones at the transmission. Look for chafing on the harness.

 

[tennmogger]

DNS is do not shift (the TCM that is, not you)

NDT, would you interpret this to indicate loss of power to the transmission ECM?

 

[dxhend2]

The P0721 (most recent error code) is interesting. Found several references saying that it's related to shaft speed sensor signal. Starting with the sensor module itself, other downstream problems could be wiring issues, etc. before it gets to the TCM. Sounds like this kind of error could be a "start veto" that would keep the starter from engaging. Another key symptom noted on several sites - could be loss of speedometer!!!, which has been our case since we've been running (we've been using my phone with a GPS speedometer app, duct taped to the dashboard, to give a large digital speed display). Speedometer has never worked since we picked up the truck. Seems like several symptoms, and all of your deductions, are pointing us in this direction.

We're safe for the night, shutdown in a parking lot a block from a hotel. Plan is to get back online and research more tonight, and be out here at first light to trace from that sensor downstream. If we need some professional help for hire, we're in the middle of Salt Lake City with more resources, and we have a better idea of what to focus on.

Thanks so much for everyone's help tonight, we really appreciate your prompt response and good ideas!! 700 miles to go...we can do this! Securing till daylight...

Sent from my 0PJA2 using Tapatalk

 

[NV555]

A1R should look like this.

Also I highly suggest Shan at Rocky Mountain trucks in Ogden. He is great with cats and Allison also owns a few MVs. If it comes down to going in for service.