P1923

Read the instructions below then start the fault diagnostic procedure.

Symptom: No bus communication with the TCM.

P1923

Fault symptoms

No bus communication with the TCM.

Conditions

The following conditions are applicable:

Trionic:

•	Engine Running

•	The TCM has previously been present on the bus at one time.

•	No communication for 3 seconds.

Diagnostic help

Some of the following symptoms may be observable:

-	Diagnostic trouble code P1921 in TCM (if TCM can be contacted).

-	Additional diagnostic trouble codes in Trionic (P1908).

-	Engine will not start.

-	Automatic transmission in limp-home mode (CHECK GEARBOX lamp on)

Check wiring harness.

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