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Home >> Jaguar >> 1996 >> XJS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self Diagnostics >> Self-Diagnostic Tests >> DTC P0123: Throttle Position Sensor Input High
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DTC P0123: Throttle Position Sensor Input High

NOTE: After each repair, clear DTCs. See CLEARING CODES/PCM RESET PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Turn ignition off and then on. Read DTCs to verify repair is complete. For DLC and PCM connector terminal identification, see CONNECTOR IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS  .
  1. Using scan tool, read DTCs. If DTC P0123 is present, monitor TP values at open throttle and at closed throttle. If values are okay, go to step  9 . If values are not okay, go to next step.
  2. Ensure TP sensor harness and connector are not damaged and connections are okay. Repair as necessary. If harness and connector are okay, go to next step.
  3. Turn ignition off. Disconnect TP sensor connector. Turn ignition on. Using DVOM, check Blue/White wire (XJR and XJ6) or Pink/Purple wire (XJS) for voltage at TP sensor connector terminal No. 3. If voltage is not 5 volts, repair wiring as necessary. If voltage is 5 volts, go to next step.
  4. Check Black/Green wire on (XJR and XJ6), or Green/Yellow wire (XJS) for voltage at TP sensor connector terminal No. 1. If any voltage is present, repair wiring as necessary. If no voltage is present, turn ignition off and go to next step.
  5. Check Black/Green wire (XJR and XJ6) or Green/Yellow wire (XJS) for continuity between TP sensor connector terminal No. 1 and PCM connector terminal No. 7. Repair wiring as necessary. If wiring is okay, check Green/Yellow wire (XJR and XJ6) or Black/Yellow wire (XJS) for continuity between TP sensor connector terminal No. 2 and PCM connector terminal No. 12. Repair wiring as necessary. If wiring is okay, check Blue/White wire (XJR and XJ6) and XJ6, or Pink/Purple wire on XJS for continuity between TP sensor connector terminal No. 3 and PCM connector terminal No. 11. Repair wiring as necessary. If wiring is okay, go to next step.
  6. Check for TP sensor connector terminal No. 2 for short to TP sensor connector terminal No. 1. Repair wiring as necessary. If wiring is okay, go to next step.
  7. Connect DVOM between TP sensor terminals No. 1 and TP sensor terminal No. 2. While monitoring DVOM display, slowly move throttle from closed to open position. If voltage does not increase smoothly, replace TP sensor. If voltage increases smoothly, go to next step.
  8. Check air inlet system and exhaust system for blockage. Repair as necessary. Repair appropriate system as necessary. If both systems are okay, go to next step.
  9. Substitute a known-good TP sensor. Clear DTCs. Turn ignition off and then on. Read DTCs. If DTC P0123 is not present, repair is complete. If DTC P0123 is present, replace PCM.
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