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DTC P1240: SENSOR POWER SUPPLY MALFUNCTION Jaguar XJR II

Testing & Diagnostics ~1208 words
  1. Disconnect Throttle Position (TP) sensor harness connector and pedal position and mechanical guard sensor harness connector. Turn ignition on. Measure voltage between pedal position and mechanical guard sensor harness connector terminals No. 2 (Black/Green wire) and No. 4 (Blue/White wire). (Схема №4) If voltage is 4.8-5.2 volts, go to step 7. If voltage is not 4.8-5.2 volts, go to next step. Also measure voltage between TP sensor harness connector terminals No. 1 (Black/Green wire) and No. 4 (Blue/White wire). If voltage is 4.8-5.2 volts, go to step 6. If voltage is not 4.8-5.2 volts, go to step 4.
  2. Turn ignition off. Disconnect ECM harness connectors EM10 and EM11. Check continuity of Blue/White wire between pedal position and mechanical guard sensor harness connector terminal No. 4, ECM harness connector EM11 terminal No. 8 and ECM harness connector EM10 terminal No. 21. (Схема №3) If continuity exists, go to next step. If continuity does not exist, repair open in Blue/White wire and retest system. Go to step 17.
  3. Check continuity of Black/Green wire between pedal position and mechanical guard sensor harness connector terminal No. 2, ECM harness connector EM11 terminal No. 12 and ECM harness connector EM10 terminal No. 20. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Green wire and retest system. Go to step 17.
  4. Ensure ignition is off and ECM harness connectors EM10 and EM11 are disconnected. Check continuity of Blue/White wire between TP sensor harness connector terminal No. 4, ECM harness connector EM11 terminal No. 8 and ECM harness connector EM10 terminal No. 21. (Схема №3) If continuity exists, go to next step. If continuity does not exist, repair open in Blue/White wire and retest system. Go to step 17.
  5. Check continuity of Black/Green wire between TP sensor harness connector terminal No. 1, ECM harness connector EM11 terminal No. 12 and ECM harness connector EM10 terminal No. 20. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Green wire and retest system. Go to step 17.
  6. Ensure ignition is off and ECM harness connectors EM10 and EM11 are disconnected. Check continuity of Blue wire between TP sensor harness connector terminal No. 3 and ECM harness connector EM11 terminal No. 11, then check continuity of Green wire between TP sensor harness connector terminal No. 2 and ECM harness connector EM10 terminal No. 10. If continuity exists, go to next step. If continuity does not exist, repair open circuit and retest system.
  7. Ensure ignition is off and ECM harness connectors EM10 and EM11 are disconnected. Check continuity of Red wire between pedal position and mechanical guard sensor harness connector terminal No. 3 and ECM harness connector EM11 terminal No. 15, then check continuity of Pink wire between pedal position and mechanical guard sensor harness connector terminal No. 5 and ECM harness connector EM11 terminal No. 16. If continuity exists, go to next step. If continuity does not exist, repair open circuit and retest system.
  8. Check continuity of Black/Yellow wire between pedal position and mechanical guard sensor harness connector terminal No. 1 and ECM harness connector EM11 terminal No. 13. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Yellow wire and retest system.
  9. Measure resistance between ECM harness connector EM11 terminal No. 14 (Black/Green wire) and the following: ECM harness connector EM10 terminal No. 20 (Black/Green wire). ECM harness connector EM10 terminal No. 21 (Blue/White wire). ECM harness connector EM11 terminal No. 8 (Blue/White wire). ECM harness connector EM11 terminal No. 10 (Green wire). ECM harness connector EM11 terminal No. 11 (Blue wire). ECM harness connector EM11 terminal No. 12 (Black/Green wire). ECM harness connector EM11 terminal No. 13 (Black/Yellow wire). ECM harness connector EM11 terminal No. 15 (Red wire). ECM harness connector EM11 terminal No. 16 (Pink wire). If resistance is more than 10 megohms, go to next step. If resistance is 10 megohms or less, repair short circuit and retest system.
  10. Measure resistance between ECM harness connector EM10 terminals No. 20 (Black/Green wire) and No. 21 (Blue/White wire), then measure resistance between ECM harness connector EM11 terminal No. 12 (Black/Green wire) and the following: ECM harness connector EM11 terminal No. 8 (Blue/White wire). ECM harness connector EM11 terminal No. 10 (Green wire). ECM harness connector EM11 terminal No. 11 (Blue wire). ECM harness connector EM11 terminal No. 13 (Black/Yellow wire). ECM harness connector EM11 terminal No. 15 (Red wire). ECM harness connector EM11 terminal No. 16 (Pink wire). If resistance is more than 10 megohms, go to next step. If resistance is 10 megohms or less, repair short circuit and retest system.
  11. Position throttle closed. Turn ignition on. Measure voltage between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 15 (Red wire), then between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 16 (Pink wire). If voltage is.28-1.08 volts, go to next step. If voltage is not.28-1.08 volts, replace throttle assembly.
  12. Position throttle to Wide Open Throttle (WOT). Measure voltage between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 15 (Red wire), then measure voltage between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 16 (Pink wire). If voltage is 3.5-4.5 volts, go to next step. If voltage is not 3.5-4.5 volts, replace throttle assembly.
  13. Position throttle closed. Measure voltage between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 13 (Black/Yellow wire). If voltage is.28-1.08 volts, go to next step. If voltage is not.28-1.08 volts, replace throttle assembly.
  14. Position throttle to WOT. Measure voltage between ECM harness connector EM11 terminals No. 12 (Black/Green wire) and No. 13 (Black/Yellow wire). If voltage is 3.5-4.5 volts, go to next step. If voltage is not 3.5-4.5 volts, replace throttle assembly.
  15. Position throttle closed. Measure voltage between ECM harness connector EM11 terminals No. 11 (Blue wire) and No. 12 (Black/Green wire), then measure voltage between ECM harness connector EM11 terminals No. 10 (Green wire) and No. 12 (Black/Green wire). If voltage is.2 volts, go to next step. If voltage is not.2 volts, replace throttle assembly.
  16. Position throttle to WOT. Measure voltage between ECM harness connector EM11 terminals No. 11 (Blue wire) and No. 12 (Black/Green wire), then measure voltage between ECM harness connector EM11 terminals No. 10 (Green wire) and No. 12 (Black/Green wire). If voltage is 4.8 volts, go to next step. If voltage is not 4.8 volts, replace throttle assembly.
  17. To energize EMS relay, connect jumper wire between ECM harness connector EM10 terminals No. 16 (Purple/Pink wire) and No. 23 (Black/Pink wire). Turn ignition on. Measure voltage between ECM harness connector EM10 terminals No. 20 (Black/Green wire) and No. 21 (Blue/White wire). If voltage is 4.8-5.2 volts, remove jumper wire and reconnect ECM harness connector EM10, then go to next step. If voltage is not 4.8-5.2 volts, check for open circuit. See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace ECM.
  18. Measure voltage between ECM harness connector EM11 terminals No. 8 (Blue/White wire) and No. 12 (Black/Green wire). If voltage is 4.8-5.2 volts, system is okay. If voltage is not 4.8-5.2 volts, check for open circuit. Repair as necessary. If circuit is okay, replace ECM.

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