P0123

THROTTLE POSITION SENSOR





Fault Symptoms.
CHECK ENGINE lamp (MIL) on.
Slow idling speed.

Conditions.
P0122
Voltage less than 0.2 V and engine speed higher than 480 rpm for more than two seconds.

P0123
Voltage more than 4.85 V and engine speed higher than 480 rpm for more than two seconds.

Diagnostic Help.
The performance of the throttle position sensor can be ascertained with an ISAT scan tool.
- Connect the 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 from unactuated to fully depressed accelerator (0.5 - 4.5 V).

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 to battery negative (B-): about 5 V
^ Battery positive (B+) to pin 2: about 12 V.

Are all voltage readings OK?
YES: Continue with point 2.
NO: Check the lead in question and repair or replace it if necessary. Then continue with point 3.





2. Check the control module's throttle position input
- Connect the 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.

- 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.

Are all readings OK?
YES: Change the throttle position sensor and continue with point 3.
NO: Check the lead in question and repair or replace it if necessary. Then. continue with point 3.





3. Final check
- Clear the diagnostic trouble code.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and 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 steps taken to rectify the fault were correct.