M1088a1 issues

[jdh91b]

Tried searching and cant find any answers, it will only charge in gear but not neutral. tcm wire 141 is supplying constant voltage to k26(neutral safety) in turn feeding k11(alternator excite) constant keeping voltage from tl35 on regulator as soon as you put it in gear voltage is turned off of wire 141 and charging is normal. Also may be unrelated but no oil pressure on gauge, low oil pressure light and flashing odometer. Any help much appreciated! Thanks!!

 

[Suprman]

The cat dealer near Bragg can plug in and diagnose. Have you gone thru the whole power breaker panel and verified everything is correct? Some of the A1 trucks have a single panel and some have individual boxes. I believe all of the A1 trucks gauges are driven thru the engine ecu canbus.

 

[sandcobra164]

I'm having a similar issue with a M1089A1P2 LTAS Cab Wrecker. It doesn't behave as your described all of the time but it does occasionally. The flashing odometer is due to drained batteries. We run into that issue quite often in the National Guard as the trucks are only run once a month most of the time. I'd be curious to learn the answer to the charging problem as well.

 

[jdh91b]

Yea could be they batteries these things are so sensitive when it comes to electrical problems. And yes all the wiring is good. Even swapped a tcm out.

 

[Suprman]

Under the spare tire is a reverse protection relay it somehow senses and adjusts charging load. This piece can go on the fritz and odd charging system issues can arise. It looks like a battery isolator.