Engine runs away once in reverse....
 

Hello,
A friend just stopped by with a 2005 3500 5.9 auto.
77750 miles.
It idles ~600rpm.Once he puts it in reverse the motor revs up and takes off.
In drive same thing. But once your at ~10 mph, the rpm come back down and the throttle works.....
Now, when he is towing his trailer, placed in drive (in high range), the throttle does nothing. He pressed the throttle to the floor, then pumped, but no go....
If he puts it in Low range with the trailer, the high idle issue, the truck will get moving, once over 10 mph, the throttle works.
Yes, he took in to the dealer, but they want to replaced the torque converter.:o
The tranny fluid was never changed since new. It seems to have a slight burnt smell and slighty dark... I don't think it's the issue.
The dealer never mentioned finding any codes, but it seems to be some sensor send the wrong signal.
Any help would be great. This guy uses his truck for his living.
Thanks
Keith

Sounds like a TQ problem. The stall converter could have a problem

Isn't it overdue for a tranny fluid change?

Does sound like excessive slip...

So, once you put the truck in gear(Reverse or D), a bad torque converter causes the motor to rev excessively without touching the throttle?

Then once the trailer was hooked up in gear(high range), the throttle WAS disconnected/did not rev the motor at all. In Low range, the truck "idled" the vehicle to ~ 10mph... THEN the throttle starts working again. Like someone plugged it back in.
Sorry if this is a common issue with the tranny... Seems odd that the throttle becomes dis activated during this time.
Just a guess. Does the computer sense the tranny torque convert issue and disable the throttle(Like a run away issue)?
Thanks for your suggestions in advance.
Keith

I must rephrase. The truck accelerates from the motor pulling so hard during this time. The engine does not simple rev up... YOU must stand on the brake pedal with both feet or the beast will spin the tires......
Thanks

Why don't you tell us what truck you're talking about...

jeep did the exact same thing, i drove it another 3 weekends (shift into neutral to stop) converter is locked up