P0123

THROTTLE POSITION SENSOR





Symptom Of Fault.
The CHECK ENGINE lamp (MIL) is on.
High idling speed.
A/C compressor does not work.

Conditions.
P0120: All-embracing DTC.
P0121 Engine running and throttle closed: >1.0 V or <0.24 V.
P0122 Engine running: <0.2 V for 5 seconds.
P0123: Engine running: >4.96 V for 5 seconds.

Diagnostic Help.
The throttle position sensor reading can be obtained on an ISAT scan tool.
- Turn the ignition switch to the ON position and then back to the OFF position.
- Connect an ISAT scan tool.
- Select "READ FUNCTIONS".
- Select "THROTTLE POSITION".
If the throttle position sensor is in perfect working order the ISAT scan tool should show the current throttle position, 10-90% (0.5 - 4.5 V) from fully up (not depressed) to fully depressed accelerator.





Diagnostic Procedure.

1. Check the throttle position sensor's ground connection and power supply
- Turn the ignition switch to the ON position and then back to the OFF position.
- Unplug the throttle position sensor's 3-pin connector.
- Take voltage readings on the connector.
^ pin 1 to B-: approx. 5 V
^ B+ to pin 2: approx. 12 V.

Are all voltage readings correct?
YES:
^ Continue with point 2.
NO:
^ Rectify the lead in question and proceed to point 3.





2. Check the control module's throttle position input
- Turn the ignition switch to the ON position and then back to the OFF position.
- Unplug the throttle position sensor's 3-pin connector.
- Connect an ISAT scan tool.
- Select "READ FUNCTIONS".
- Select "THROTTLE POSITION".
The reading obtained on the ISAT scan tool should be about 99%.
- Connect a jumper lead between pins 2 and 3 of the throttle position sensor's connector.
The reading obtained on the ISAT scan tool should be about 0%.





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

Has the diagnostic trouble code recurred?
YES:
^ Proceed at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO:
^ The remedial measure taken was correct.