2010 Peterbilt 387 ISX CM871 Lost ECM Power

[runningman777]

Monday my 2010 Peterbilt 387 with an ISX-15 CM871 suddenly died with no speedometer or tach. Engine crank with no start, and the priming pump would not run. I found no BAT + to the 4 pin ECM connector. To get off the side of the road - very windy and snowing - I ran +12V thru a 15A fuse from the mega fuses to the ECM and moved to a rest area. The next morning I had a brief shut down with a red warning on the display but by time I got to the side of the road it was back running. Didn't get but a brief glimpse of the dash as I was trying to steer to the side of the road in snow. Delivered the load and made it home OK for a total of about 1,000 miles since the first shut down.

I'm assuming there's a fusible link somewhere that either opened or got corroded.

I don't have Insite but do have a diagnostic tablet to check codes.

I had 4 codes, none were active:

2374 2X Exhaust Gas Bank 1 Pressure Sensor 1 Circuit - Voltage Below Normal or Shorted to Low Source.

2448 5X Coolant Level - Data Valid But Below Normal Operating Range - Least Severe Level

197 18X Coolant Level - Data Valid But Below Normal Operating Range - Moderately Severe Level

2554 3X Exhaust Gas Bank 1 Pressure Sensor 1 Circuit - Data Erratic, Intermittent, or Incorrect

The two for low coolant was from actually running a little low.
The other two are both for exhaust gas pressure. Truck is de-mandated.

I checked the wiring to the exhaust pressure sensor and the pigtail has been replaced and the splices look good.

I'm going to look at as much of the sensor wiring that I can expose looking for possible shorts.

I would think that the ECM would current limit a shorted sensor wire so as not to allow it to blow a fuse or fusible link. Those codes may not be related to the power loss but that's just a possible lead for me to follow.

I do not have accurate schematics for my truck. The ones I've been able to find are close but they don't actually show the path thru fusible links. The only fuse for the ECM is switched ignition and it's only 5 amps.

This truck has a battery isolator switch and there's two smaller wires there - could they be BAT+ going to the ECM? I don't know if those wires are stock or somebody's jury rig...

My ESN is 79365436, VIN 1XP7D49X1AD793392

Any assistance and accurate schematics would be greatly appreciated!