Code 6600

[Burker99]

I have a 2001 Monaco Knight with a 5.9 Cummins and a Allison 3000. Over this past weekend while in heavy traffic I had my exhaust brake on. As I left a stop light I got a slight hesitation that felt like loss of power. It was only about 200 yards to my turn into the campground. I put the RV in neutral to check in. When I returned and put it in drive it clunked into gear. I checked reverse and the same thing. Also the same when backing into the site.

When we left the tranny seemed to work good. With cruse on in economy mode at about 62 mph. Some down shifts 6-5 on rolling hills but I have noticed that when pulling my 4K toad.

I checked for codes and have a 6600 communication code. I cleared it but have not driven to see if it reoccurs.

Here is my major concern. I am leaving (I hope) for a 5000 mile trip next week. Is it safe to drive the RV if this happens again. The local Allison shop can't get me in for over a week. If I have to postpone I will but I am hoping not.

I have read about checking wiring connections and I will do that as soon as it stops raining.

Your help is truly appreciated.

Phil

[dbarton291]

I assume the control system is WTEC III based on the vehicle model year.
Code 66 indicates the trans controller is expecting to see a throttle signal or an engine coolant signal over a serial communication link from the engine controller.
Either the engine controller is not sending the signal, or the communication link wiring has a problem.
One note about 66-00 specifically. This can occur if the trans controller is powered while the engine controller is not. If the engine controller has a power interrupt, or the timing of the ignition signal to the engine controller is being interrupted by something, this can occur.
The most likely scenario would be the wiring between the controllers. Those circuit numbers (Allison circuit numbers) are 142 and 151. Those may have a solid or intermittent open, short to other wires or short to ground.