800B CDR23: Diagnosis/troubleshooting

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2005 Porsche 911, 2004 Porsche 911, 2003 Porsche 911, 2002 Porsche 911, and 2001 Porsche 911. However, it is still accessible from the selected car via links, so may be relevant.

DIAGNOSIS/TROUBLESHOOTING (800B CDR23)

Work instruction			Display OK	If not OK
1	Check CAN comfort leads, CAN comfort (high) and CAN comfort (low) for short circuit	Switch off ignition. Remove plug A from instrument cluster. Pull plug off the Tiptronic control module. Pull plug off the PSM control module. Pull off plug on steering-angle sensor. Pull plug off the DME control module. Measure resistance on plug A of the instrument cluster between pin 15 and pin 31. Measure resistance between pin 3 and pin 4 of plug B on the DME control module.	Step 2	Repair wiring harness -> End
2	Check CAN comfort lead, CAN-high for short to ground	Measure resistance between pin 15 and ground of plug A on instrument cluster. Measure resistance between pin 3 and ground on plug B of the DME control module.	Step 3	Repair wiring harness -> End
3	Check CAN comfort lead, CAN-low for short circuit to B+	Switch on ignition. Measure resistance between pin 31 and ground of plug A on instrument cluster. Measure voltage between pin 3 and ground on plug B of the DME control module.	0 V Step 4	Repair wiring harness -> End
4	Determine faulty control unit	Switch off ignition. Reconnect all plugs to control units. Pull off plugs to the control units (except instrument cluster) individually and read out the fault memory of the instrument cluster and check whether the fault has been remedied.	The fault is remedied by disconnecting the plug connection of a control unit. Step 5	The fault is still present Step 6
5	Replace the control module that was last disconnected from CAN comfort		-> End
6	Replace instrument cluster		-> End