8004 CDR23: Diagnosis/troubleshooting

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 vehicle type 911 (996) and start the automatic control unit search In the Control units menu, select CDR23 Click the "> >" key in the Fault memory menu 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 bus 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 units (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 unit Step 8	Step 9
8	Replace the control unit which was last disconnected from the CAN bus.		-> End
9	Replace CDR23		-> End