My brother-in-law has a 2013 GMC 3500 with Allison diesel. He sometimes gets the "engine
loss of power" alarm but only when pulling his 28 ft 5th wheel RV. GM seems to be aware of the issue but has no idea what the problem is. When it happens, he pulls off to the shoulder, turns the engine off, waits at least 3 minutes, goes through some sequence with the ignition switch and simultaneously depressing the brake
and accelerator pedals, starts the engine and goes until it happens again. Sometimes he can go a few hours, sometimes a few miles and sometimes less than a half mile. after as many as 5 consecutive times in less than a hour, it seems to be ok but will repeat the process later in the day or the next day. This is getting to be a dangerous situation when traveling on interstates, through metro areas or on 2 lane roads with little or no shoulder. Does anybody know what to do to fix this problem?
JA: Has the car been stalling out?
Customer: It loses speed and power
JA: Are you fixing your 3500 yourself? What have you tried so far?
Customer: No. have taken to personal mechanic who has replaces a solenoid, talked with dealership mechanics and has contacted GM directly.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Can't think of anything else .