Hi everyone

I am trying to help an engineer out who is working on an engine truck (not my field) the serial is 100040105.

The problem is it drives in forward ok, but as soon as he tries to drive it in reverse the transmission warning light comes on and does not drive. After switching off and restaring it will work again inf forward as it did but the same thing happens as soon as he puts it into reverse.

Can someone shed some light on this issue please and would someone be able to send me a pdf version of the service manual or info related to this error, would be appreciated greatly.

Regards