I just repair the AD-6 fault, caused first by loose and dirty fuse, coupled to the material control system, such a fuse because it is dirty and loose caused several faults in the forklift such as AD-5 (After failure AD- 6), the flow diagram to repair the fault says that you must look for false contacts, because the material control system is in trouble, for this you must first check the communication of the CN101 connector cards and CN111 connector

i have a toyota 7FBEU15 showing error codes AD-1 and AD-2

Have a look at the main contactor in the electrical panel in the back.

Remove the inspection covers & you will see it.

Ive changed a couple of these contactors on Traigo 48s over the years.

If you unscrew the contactor to remove it, make sure you don't loose the clear plastic insulator sheet mounted behind it.

Also check the blade fuses in the black fuse holders, ive had the terminals in the fuse holders on older / high hours Traigo 48 spread slightly causing odd electrical faults over bumps.

My forklift model 8FBMT20 showing error AD-2,AD-6,AD-1,AD-5,CB-5.Please help me to diagnose this error.

Don't know about your diesel truck.

have a Toyota 02-8FDF diesel error code 71-1. Advise where to look? I assume that this sensor inversion wheels. Sorry for the language I'm from Ukraine. Can you have a list of codes?

All these error codes were due to the damage of the main controller (controller itself and some wires), which just above the real wheel. have to fix the broken wires and repair the main controller $300 cost.
'AC' - semiconductor switch abnormality
'AD-2' 'AD-4' - traveling AC driver to main controller communication abnormality
'AD-6' - material handling AC driver to main controller communication abnormality.