Circuit Description

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and monitors the TP signal circuit for changes in throttle angle. TP sensor signal voltage should be about.6 volt at idle and 4.5 volts or greater at wide open throttle. DTC P0121 will set if TP sensor angle is greater than a specified percentage at a given engine speed.

For duplication of DTC, ensure:

• Engine is operating on alternative fuel.
• No Alternative Fuel Electronic Control Unit (AFECU) DTCs are set (with the exception of DTCs P1215, P1432 and P1433).
• Engine MAP is less than 45 kPa.
• TP sensor angle has changed less than 2 percent in 2 seconds.