P0123

THROTTLE POSITION SENSOR





Fault Symptoms
CHECK ENGINE lamp (MIL) on.
Fast idling speed.
A/C compressor does not work.

Conditions.
P0122
Shorting to ground
Throttle position < 1.2% / < 0.06 V.

P0123
Shorting to battery positive (B+)/open circuit
Throttle position > 95% / > 4.75 V.

Diagnostic Help.
The position of the throttle position sensor can be ascertained with an ISAT scan tool.

- Connect an ISAT scan tool.
- Turn the ignition switch to the ON position.
- Select "READ FUNCTIONS".
- Select "THROTT POS SENSOR".

If the throttle position sensor is in proper working order the ISAT scan tool should show the current throttle position, between about 0.5 V and 4.5 V from unactuated to fully depressed accelerator.

Check the Wiring
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.





Diagnostic Procedure.
1 Check the throttle position sensor's ground connection and power supply

- Unplug the throttle position sensor's 3-pin connector.
- Turn the ignition switch to the ON position.
- Take voltage readings on the connector as follows:
^ pin 1 and battery negative (B-): about 5 V
^ 5GBattery positive (B+) and pin 2: about 12 V.

Are all readings OK?

YES:
^ Continue with point 2.

NO:
^ Check the relevant lead and repair or replace it if necessary. Continue with point 3.





2 Check the electronic control module's throttle position input

- Connect an ISAT scan tool.
- Turn the ignition switch to the ON position.
- Select "READ FUNCTIONS".
- Select "THROTT POS SENSOR".
The ISAT scan tool should show a reading of about 5 V (about 100%).
- Connect a jumper lead between pins 2 and 3 of the throttle position sensor's connector.
The ISAT scan tool should show a reading of about 0 V (about 0%).

Are all readings OK?

YES:
^ Change the throttle position sensor. Continue with point 3.

NO:
^ Check the relevant lead and repair or replace it if necessary. Continue with point 3.





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:
^ Continue at "Procedure Before Replacing a Control Module". Component Tests and General Diagnostics

NO:
^ The steps taken to rectify the fault were correct.