Test Description
Number(s) below refer to step number(s) on Diagnostic Table.
- 1. The On-Board Diagnostic (OBD II) System Check prompts technician to complete some basic checks and store freeze frame and failure records data on scan tool if applicable. This creates an electronic copy of data taken when malfunction occurred. The information is then stored on scan tool for later reference.
- 2. The TP sensor has an auto zeroing feature. If voltage reading is between .2 to 0.9 volts, PCM/ECM will assume TP sensor is at a closed throttle position (0%). If reading is out of auto zeroing range at closed throttle, look for a binding or damaged linkage.
- 3. Normal TP voltage when throttle plates are fully closed is near .5 volt. A sensor will display a higher voltage when sensor is stuck or a circuit is faulty.
- 5. A disconnected TP sensor should not display a voltage reading on scan tool. An amount less than specified value is normal.
- 6. When test light is connected to ground circuit, light should glow brightly if ground circuit is okay but could have a small amount of resistance in circuit. The voltmeter is used to detect small amounts of resistance using voltage drop method. If test light glows dimly or not at all, then resistance in circuit is present and using voltmeter is not necessary.
- 7. In order for DTC P0121 to set with a short voltage in TP signal circuit, voltage must be minimal enough to not set a DTC P0123 and must be more than .5 volt.
- 13. The replacement PCM/ECM must be reprogrammed.
- 15. If no faults have been found at this point and no additional DTCs were set, refer to "Diagnostic Aids" for additional checks and information.