8004 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 (8004 CDR23)

Work instruction			Display OK	If not OK
1	Read out CDR23 fault memory	Connect and start the Porsche System Tester II 9588 and switch on the ignition. Select 911 (996) in the Vehicle type menu and confirm with the "FORWORD" key. Select CDR23 in the Control units menu and confirm with the "FORWORD" key. Select Fault memory in the 911 (996) CDR23 function selection and confirm with the "FORWORD" key. Read out fault memory. Erase fault memory. Remove ignition key and switch on ignition again. Read out fault memory.	-> End	Fault code is displayed Step 2
2	Check CAN comfort leads, CAN (high) and CAN (low) for short circuit	Switch off ignition. Pull off plug E on CDR23. Pull off plug on instrument cluster. Pull off plug on Climatronic. Measure resistance on plug E of CDR23 between pins 1 and 2.	Step 3	Repair short circuit in wiring harness between high and low -> End
3	Check CAN comfort (high) for short circuit to ground	Measure resistance on plug E of CDR23 between pin 1 and ground.	Step 4	Repair short circuit between CAN comfort (high) and ground -> End
4	Check CAN comfort (low) for short circuit to ground	Measure resistance on plug E of CDR23 between pin 2 and ground.	Step 5	Repair short circuit between CAN comfort (low) and ground -> End
5	Check for short circuit between CAN comfort (high) and battery positive connection	Measure voltage on plug E of CDR23 between pin 1 and ground. Switch ignition on.	< 0 V Step 6	Repair short circuit between CAN comfort (high) and voltage supply line -> End
6	Check for short circuit between CAN comfort (low) and battery positive connection	Measure voltage on plug E of CDR23 between pin 2 and ground. Switch ignition on.	< 0 V Step 7	Repair short circuit between CAN comfort (low) and voltage supply line -> End
7	Determine faulty control unit	Switch off ignition. Reconnect all plugs to control units. Pull off plugs to the control modules (except CDR23) individually and read out the fault memory of CDR23 and check whether the fault has been remedied.	The fault is remedied by disconnecting the plug connection of a control module Step 8	Step 9
8	Replace the control module that was last disconnected from CAN comfort		-> End
9	Replace CDR23		-> End