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Home >> Lexus >> 2004 >> IS 300 Base, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 8 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P1121: Accelerator Pedal Position Sensor Range/Performance Problem >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check accelerator pedal position sensor operation. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If accelerator pedal position sensor is okay, go to next step. If accelerator pedal position sensor is not okay, go to step  3.
  2. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between terminals No. 22 (Blue/Yellow wire) and No. 28 (Light Green/Black wire), and terminals No. 23 (White/Red wire) and No. 29 (Light Green wire) at ECM connector E6. See Figure. With fully closed throttle, voltage should be .5-1.1 volt (terminals No. 22 and 28) or .9-2.3 volt (terminals No. 23 and No. 29). With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts (terminals No. 22 and No. 28) or 3.4-5.0 volt (terminals No. 23 and No. 29). If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Disconnect ECM E6 connector. Ensure continuity is present in wiring between ECM and accelerator position sensor. See WIRING DIAGRAMS article. If continuity is not present, repair wiring as necessary. Check continuity (backprobe) between ground and terminals No. 28 (Light Green/Black wire) and No. 29 (Light Green wire). No continuity should be present. Repair wiring as necessary. If wiring is okay, replace accelerator pedal assembly.
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