Fault code 34: Diagnosis/troubleshooting

FAULT CODE 34 DIAGNOSIS PROCEDURE

Work instruction			Display OK	If not OK
1	Check CAN bus leads, CAN-high and CAN-low for short circuit	Switch off ignition Remove plug A from the instrument cluster Remove plug of the air-conditioning system regulator Measure resistance on plug A of the instrument cluster between pin 14 and pin 30	Step 2	Repair wiring harness -> End
2	Check CAN bus lead, CAN-high for short to ground	Measure resistance between plug A on instrument cluster pin 14 and ground	Step 3	Repair wiring harness -> End
3	Check CAN bus lead, CAN-low for short to B+	Switch on ignition Measure voltage between plug A on instrument cluster pin 30 and ground	0 V Step 4	Repair wiring harness -> End
4	Determine faulty control unit	Switch off ignition Reattach the plugs on instrument cluster Read out fault memory from instrument cluster and check whether the fault "CAN Comfort Bus" has been remedied.	Fault has been remedied Step 5	The fault is still present Step 6
5	Replace air-conditioning system regulator		-> End
6	Replace instrument cluster		-> End