800B CDR23: Diagnosis/troubleshooting
DIAGNOSIS/TROUBLESHOOTING (800B CDR23)
| Work instruction |
Display OK |
If not OK |
| 1 |
Check CAN bus leads, CAN-high and CAN-low for short circuit |
- Switch off ignition
- Pull plug A off instrument cluster
- Pull plug off Tiptronic control unit
- Pull plug off PSM control unit
- Pull plug off steering angle sensor
- Pull plug off DME control module
- Measure resistance between pin 15 and pin 31 on plug A of instrument cluster
- Measure resistance between pin 3 and pin 4 on plug B of DME control module.
|
Step 2 |
Repair wiring harness
-> End |
| 2 |
Check CAN bus lead, CAN-high for short to ground |
- Measure resistance between pin 15 on plug A of instrument cluster and ground
- Measure resistance between pin 3 on plug B of DME control module and ground
|
Step 3 |
Repair wiring harness
-> End |
| 3 |
Check CAN bus lead, CAN-low for short to B+ |
- Switch on ignition
- Measure resistance between pin 31 on plug A of instrument cluster and ground
- Measure voltage between pin 3 on plug B of DME control module and ground
|
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 control units (except instrument cluster) individually and read out fault memory of instrument cluster and check whether fault has been remedied.
|
The fault is remedied by disconnecting the plug connection of a control unit.
Step 5 |
Fault is still present Step 6 |
| 5 |
- Replace the control unit which was last disconnected from the CAN bus.
|
-> End |
| 6 |
- Replace instrument cluster
|
-> End |