P0506

IDLING SPEED INCORRECT





Fault Symptoms
Fast, slow or hunting idle speed.
Idle speed sensitive to load changes.
Possibly other diagnostic trouble codes, adaptation, misfiring.

Conditions.
P0506
^ Vehicle speed = 0 km/h.
^ Coolant temperature above 80°C (176°F).
^ Purging (EVAP), not active.
^ Engine speed more than 200 rpm below requested revs.

P0507
^ Vehicle speed = 0 km/h.
^ Coolant temperature above 80°C (176°F).
^ Purging (EVAP), not active.
^ Engine speed more than 100 rpm above requested revs.





Diagnostic Help.
The idle air control valve can be activated with the Tech 2.
- Select "ACTIVATE".
- Select "IAC VALVE".
The command activates the valve at a frequency of 0.5 Hz for 30 seconds.

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 air supply
- Check that hoses to and from the IAC valve are correctly fitted and not kinked or pinched, which could result in more/less air being supplied.
- Check the operation of the throttle valve,

Is throttle valve operation OK?
YES
^ Continue with point 2.
NO
^ Rectify any faults.
Continue with point 4.





2. Check the idle air control valve's power supply
- Unplug the valve's 3-pin connector.
- Turn the ignition switch to the ON position.
- Connect a test lamp to the connector between:
^ pin 2 and battery negative (B-).
The test lamp should light up.

Did the test lamp light up?
YES
^ Continue with point 3.
NO
^ Repair or replace the lead between the 3-pin connector and crimped connection J128. Continue with point 4.





3. Check the control module's outputs to the idle air control valve
- Connect a test lamp to the female connector between:
^ B+ and pin 1
- Connect the Tech 2.
- Turn the ignition switch to the ON position.
- Select "ACTIVATE".
- Select IAC VALVE".
The test lamp should flash at a frequency of 0.5 Hz for 30 seconds.
- Repeat the above procedure with the test lamp
connected to the female connector between:
^ B+ and pin 3
The test lamp should flash at a frequency of 0.5 Hz for 30 seconds.

Is the test lamp flashing?
YES
^ Change the idle air control valve.
Continue with point 4.
NO
^ Check the relevant lead and repair or replace it if necessary. Continue with point 4.





4. Final check
- Clear the diagnostic trouble code.
- Implement a driving cycle:
^ The engine should have attained normal operating temperature.
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Switch off the engine.
- Start the engine and run it at idling speed for about 45 seconds. Repeat this 3 times.
- 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.