Vehicle: 1994 TripleE RV based on Ford E350 7,3 Diesel, 70000 miles.

My trans is skipping out of lockup for 1-2 Seconds and then goes back to normal operation with lockup engaged. I am shure that it is the lockup disengaging because the increase in rpm is not as much as between gears.

This happens appr once or twice every hour when driving at normal constant highway speed. It happens both in 3rd and in OD. There is no flashing OD lamp, and the OD button is working (I use this activly when going up hill to keep up momentum and rpm)

I am not able to find out what causes this. I have replaced the speed sensor on the rear axle, the rpm sensor on the engine and the brake light switch on the brake pedal. Replaced one item at the time to be able to determine if any of these items was causing the problem. But none of them made any difference, the problem is still there. I have also inspected the harness connector on the trans and it seems fine to me.

I try to search the forum (both this and the 7.3 IDI section) for any similar problems and hopefully solutions, but with no luck. Found one thread with the same symptoms, but the guy had given up without finding any solution.

Anyone out there who has any idea what causes this?

Thanks,
Lars Petter
Norway

 

It could be a failing FIPL sensor. That's the sensor on the side of the injection pump. The converter will unlock if there is a sudden change in pedal position. If the sensor has a bad spot that can create a false sudden change.