I have a fleet of these toyotas, and this is a new one for me. Truck operates fine for about 5-10 minutes. The it will randomly shut down, disabling travel and power steering, and display codes AC-1, AD-1 & AD-5. Then you key off and back on, the truck then shows CB-2, and beeps but does operate. Re-key truck again, and it clears all codes and will operate fine for approx 5 min or less.
The only pattern I can find is that it seems to do this on declaration. Mostly when you slow down for a stop sign, or an upcoming turn. I believe its in the drive circuit, however the service manual is very vague on troubleshooting these problems.
Any advise, suggestions, anything? Im about to start swapping parts with anther truck until I figure this one out. But I hate doing that.
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Your main contactor solenoid is shorting out and spoofing components down-stream. I'm posting a link for the OEM part below. It's possibly the other components may be damaged (pump driver driver, motor drive driver, etc) but replacing this part is a good place to start.
https://shop.toyotaforklift.com/en/categories/forklift-parts-accessories/other/contactor-kit/p/005905684271
The codes are as follows:
AC-1: Semi-conductor switch abnormality
AD-1 Driver Motor Driver Communication Abnormality
AD-5 Pump Motor Driver Communication Abnormality
CB-2 MB (main Contactor) short
Hi....I have a 8FBCU25. Unit will not drive or lift...key on unit displays error code AD1 and AD2....can anyone help...
FOUND THE PROBLEM -
Sorry for the delayed response. So after lots of troubleshooting, parts swapping, phone calls, and even help from a toyota dealer, no one could figure this **** truck out, until I accidentally bumped a harness and found the open/short that was causing the issue. There is a little black box that houses a small circuit board, and is mounted right in front of the AC drive controller. I've been told this board starts charging the capacitors on key up. However the Toyota manual only refers to it as "Board". Anyway, there was a poor solder joint on the circuit board where the harness plugs into it. I noticed it when slightly tugging on that harness would cause the faults to display even when not driving.
I remove this unit, and swapped with another truck, and all is running fine. Has been for about 2 months now with no issues.
By the sounds of things you may want tot check the mb contactor. It may be closing but not making a good connection. I would also check the fuses and make sure they are secure.
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