Fault Conditions

No Bus Data From MIU. See Fault Tracing, Bus and Diagnostic Communication.
See Powertrain Management/Computers and Control Systems/Information Bus/Testing and Inspection/Procedures/Fault Diagnosis, Diagnostic Trouble Codes/P1908 No Bus Data from MUI.







Fault symptoms
Some of the following symptoms may be observed:
- Engine will not start.
- Cruise control not working.
- A/C malfunctioning.
- Radiator fan runs continuously.
- Main instrument unit gauges and indicators not working.
- Additional trouble codes in Trionic (P1901).
- Additional trouble codes in TCM (P1902 or P1923).
- CHECK ENGINE.

On-Board Diagnostics
Type of diagnosis:
- Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria:
- Engine running.

Fault criteria:
- No communication for more than 3 s.

Dependents:
- None.

System reaction to a fault:
- Cruise control blocked.

OK report:
- Enable criteria fulfilled and fault criteria not fulfilled within 60 s.

Fault handling: Fault Handling III, Other Emission-Related Component & Function
- Type III.

Diagnostic help
Fault diagnosis concerns an intermittent electrical fault in the power supply to the transmitting control module or any of the bus leads.

Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.

Diagnostic procedure
For more detailed fault diagnosis, see "Bus and diagnostic communication P1908".
See Powertrain Management/Computers and Control Systems/Information Bus/Testing and Inspection/Procedures/Fault Diagnosis, Diagnostic Trouble Codes/P1908 No Bus Data from MUI.