Last week we were driving our 2003 Chevy Express 3500 Roadtrek RV to Sequoia National Park - a steep, curvy, long road with a lot of altitude gain. Shifter in second gear. I was keeping my eyes on the coolant temp - I swear it never got over 3/4 up the gauge. Engine started loosing power, and after about a minute or two of worsening power, the engine just stopped. Check engine light came on as the motor did the final wheeze. In the lane on a tight two-lane mountain road, with nowhere to pull over. Starter would not engage or make any sound. Opened the hood, and it was really hot under there, but not the smoky, gurgling, steaming sort of hot I'd expect of an engine overheat. Let it cool for maybe 5 minutes, and it started up, made it about a quarter of a mile, and croaked again. Waited 5 minutes, made a u-turn, and headed back downhill. Didn't have any more trouble on the rest of the trip - 700 miles.

Check engine code was for a misc misfire, no limp-home or codes where the system may have recognized a problem and did something about it by shutting down.

I'm having a hard time believing that this was an engine coolant overheat, it wasn't feeling like that under the hood, and the temp gauge wasn't in the red. My only crazy thought is that the transmission got so hot climbing and never going into overdrive that it caused heat soak and engine electricity stopped flowing somewhere. Might explain the starter not doing anything. Transmission fluid was low. I'm having the tranny serviced and adding an external transmission cooler just because.

We've put 10,000 miles on this vehicle, been to Yosemite twice, and over the Sonora pass without any trouble. I spoke to my mechanics and a transmission guru, and they are stumped.

Anybody experienced something like this? I really need to figure this out - it was a pretty scary experience.

Thanks!
Steve

 

It seems to be an electrical problem. I would consider replacing the battery and also checking over all of the major positive and negative connections.

 

Thanks, SteveROntario. It is starting to sound like a transmission overheating problem - the mystery is why the starter was cut out completely. A bad electrical connection that is heat sensitive, or heat soak of the starter could explain it.

 

If the Junction Box Relay (Underhood Fusebox) does not send 12+ to the Starter Solenoid then the Starter will not engage right? The Junction Box Relay gets it's 12+ Signal from the ECM or the BCM, I forget. If it is the ECM and it was simply too hot, that might explain things.

 

Neutral safety switch? In the heat of the moment did you put it in park or neutral?

 

I didn't know the starter relay was energized by the engine control module - I'll dig into that.

No, not the neutral switch - I'm positive it was in park. Good thinking, though!

Thanks for your thoughts!