Hand Control Unit ECU - Checksum or Counter Failure
Check short-circuits and open-circuits on CAN lines to the HCU and assure that HCU works correctly.
What you'll see
No driver-visible symptom recorded.
System reaction
HCU is not used, manual functions are not available. Red warning lamp.
Diagnostic depth
CRC or message counter error in HCU Information message from HCU. When cheksum calculated by EPB ECU is different from the checksum received with the message - fault is set immediately. Fault is also set when a counter received with the message does not equal the next counter value for the previous message - at least two times. Furthermore, the fault will be set when the message is received faster than the nominal update rate and at least one message was lost. Clearing checksum fault requires two following messages with correct checksum and counter values with nominal update rate.
Electromagnetic disturbance, HCU sends invalid values because of an internal reason or error