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DTC P0121/16505: TP Sensor Circuit Range/Performance Problem

WARNING: This page is about a different variant/trim than selected.
NOTE: DTC is set when Throttle Position (TP) sensor supplies invalid signal to Electronic Control Module (ECM).
  1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. Erase DTC memory and test drive vehicle. See CLEARING DTCS  under INTRODUCTION. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to next step. If sensor connector is okay, go to next step.
  2. Turn ignition off. Disconnect Throttle Valve Control Module (TVCM) connector. Turn ignition on. Using DVOM, check voltage between TVCM connector terminals No. 4 and 7. Voltage should be about 5 volts. Check voltage between TVCM connector terminals No. 3 and 7. Voltage should be about 10 volts. If voltage is as specified, go to step 6). If voltage is not as specified, go to next step.
  3. Turn ignition off. Disconnect ECM connector. Connect Test Box (VAG 1598/18) to ECM wiring harness. Terminal assignments of test box are identical to ECM connector's.
  4. Check resistance between TVCM connector terminal No. 3 and test box socket No. 10, between TVCM connector terminal No. 4 and test box socket No. 41, and between TVCM connector terminal No. 7 and test box socket No. 33. Resistance should be less than 1.5 ohms. If resistance is as specified, go to step 9). If resistance is not as specified, go to next step.
  5. Check for an open circuit between TVCM and ECM. Repair as necessary. Erase DTC memory and test drive vehicle. See CLEARING DTCS  under INTRODUCTION. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to next step. If no open circuit is present, go to next step.
  6. Turn ignition off. Reconnect TVCM connector. With accelerator at Wide Open Throttle (WOT) and at closed throttle, check resistance between test box sockets No. 10 and 33. Resistance should be infinite (no continuity) at WOT and 10 ohms maximum at closed throttle. If resistance is as specified, go to step 9). If resistance is not as specified, go to next step.
  7. With accelerator pedal at closed throttle, check resistance between test box sockets No. 27 and 53. If resistance is 3-200 ohms, go to step 9). If resistance is not as specified, go to next step.
  8. Disconnect TVCM connector. Check resistance between TVCM connector terminal No. 1 and test box socket No. 27, TVCM connector terminal No. 2 and test box socket No. 53, TVCM terminal connector No. 5 and test box socket No. 40, and TVCM connector terminal No. 8 and test box socket No. 62. Resistance should be less than 1.5 ohms. If resistance is not as specified, locate and repair open circuit between TVCM and ECM. Erase DTC memory and test drive vehicle. See CLEARING DTCS  under INTRODUCTION. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to step 11). If resistance is as specified, go to next step.
  9. Check resistance between test box sockets No. 10, 27, 33, 40, 41, 53, and 62. Resistance should be infinite (no continuity) between each circuit. If resistance is not as specified, repair circuits shorted to each other. Erase DTC memory and test drive vehicle. See CLEARING DTCS  under INTRODUCTION. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to step 11). If no shorts are present, go to next step.
  10. Substitute a known-good TVCM. Clear DTCs and perform test drive. See CLEARING DTCS  under INTRODUCTION. Recheck DTC memory and verify DTC does not reset. If DTC resets, check MAF and ECT. See DTC P0102/16486  , P0103/16487, P0117/16501 and P0118/16502.
  11. Replace faulty ECM. Test drive vehicle. Recheck DTC memory and verify DTC does not reset. If DTC resets, repeat testing procedure.
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