Automatic Gearbox Trip Out When Towing

[dashwoodchris]

I have experienced trouble for 6 months now that my dealer can't fix.

When towing my Caravan the auto gearbox will lock into safe mode (gears won't change) until i stop turn ignition off and re-start again. This can be done immediately and so i don't think it's a gearbox problem.

This ONLY happens when towing and only occurs in 4th gear of the auto box.

When travelling solo this problem never occurs.

Has anyone any ideas?

Chris.