Engine speed dipping, DRIVE

Engine speed dipping, DRIVE

Fault symptoms

Engine idling speed drops when the selector lever is moved from P or N.

Conditions

Short circuit to ground or open circuit.

Diagnostic procedure

1 Check the output signal from the control module

-	Connect a diagnostic tool.

-	Turn the ignition to the ON position.

-	Select " Data Display / Output Control (New)".

-	Select " Drive Signal". The diagnostic tool should read OFF with the selector lever in positions P and N, and ON with the selector lever in positions R, D, 3, 2, 1.

Are the readings correct?

Yes

Continue with step 3.

no

Continue with step 2.

2. Check the input signal to the engine management system

-	Unplug the connector from the engine control module.

-	Turn the ignition to the ON position.

-	Connect a test lamp to the connector as follows: Motronic: between pin 47 and pin 27 Trionic: between pin 14 and pin 60 The test lamp should light up when the selector lever is in position P and N but not in other positions.

Is the signal correct?

Yes

Continue fault diagnosis in Service Manual 2:7 "Engine management system". Then continue with step 4.

no

Rectify the relevant lead and continue with step 3.

3 Final check

-	Clear all diagnostic trouble codes in the system.

•

Perform a check of functionality.

All OK?

Yes

The steps taken to rectify the fault were correct.

no

Continue with Diagnostic procedure before replacing control module