P1603

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE. Incorrect idle speed. Cruise control inoperative.

P1603

Fault symptoms

•	CHECK ENGINE.

•	Incorrect idle speed.

•	Cruise control inoperative.

On-Board Diagnostics

Type of diagnosis:

-	Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria:

-	Ignition in ON position.

Fault criteria:

-	ROM faulty in processor 592.

Dependents:

-

None.

System reaction to a fault:

-	Throttle control goes into limp-home mode. The limp-home solenoid will be activated 5 times in succession each time the ignition is turned on until the fault has been rectified and the trouble codes cleared.

OK report:

-	Accelerator pedal has been depressed at some time and then fully released. 120 s has expired since then without fault criteria being fulfilled.

Fault handling: (See “Fault diagnosis, general” for more information.)

-	CHECK ENGINE goes on immediately and can be turned off only by clearing the trouble codes.

Diagnostic help

Fault diagnosis concerns an internal fault in the control module.