P1657

CONTROL MODULE OUTPUT, WRONG CONNECTION





Fault Symptoms
None.

Conditions.
A control module output which should not be used is connected.

Diagnostic Help.
The diagnostic trouble code is generated if a control module output which should not be used is connected.
The diagnostic trouble code indicates a wrong control module connection or a wrong control module version.
The Tech 2 can be used to find out which control module version is used.

Check The Wiring.
Intermittent faults may occur as a result of occasional short circuits and breaks in the wiring. Jiggle the leads and in-line connectors at several places and in different directions to reveal faults in the wiring harness.
Observe the multimeter, Tech 2 diagnostics instrument or test lamp while carrying out this check.





Diagnostic Procedure.
1. Check the control module connections
- With the aid of "Control Module Connection Test Readings,", check whether pins which should not be used are connected. Pinout Values and Diagnostic Parameters

Are the connections OK?
YES
^ Continue with point 2.
NO
^ Rectify any wrong connection. Continue with point 3.





2. Check the control model version
- Check that the correct control module version is fitted.

Is the correct version fitted?
YES
^ Continue with point 3.
NO
^ Change the control module. Continue with point 3.





3. Final check
- Clear the diagnostic trouble code.
- Implement a driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluate the driving cycle:
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?
YES
^ Continue with "Before Replacing A Control Module".Component Tests and General Diagnostics
NO
^ The steps taken to rectify the fault were correct.