I’m working on a Caterpillar ADEM III ECM that currently has no signal on the CAN bus (CAN_H and CAN_L). I suspect the problem is in the power supply section, specifically the UC3843B PWM controller, which may not be switching correctly. This IC controls the regulated 5 V rail that powers the AN82527 CAN controller and other logic.
Right now, the AN82527 does not seem to power up fully — so TX0/RX0 have no activity and the CAN lines stay inactive.
I’m looking for:
- Ideas to properly diagnose this issue.
- Possible common faults in ADEM III ECMs that usually cause no CAN signal or problems in the power supply stage.
- Any advice on how to check the switching circuit and ensure stable Vcc for the CAN controller.
Any suggestions or troubleshooting tips would be very helpful.
Thanks in advance!
