Code 21

This DTC flashes the CHECK TRANS indicator and sets the BACKUP MODE.

CIRCUIT DESCRIPTION:
- The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle plate position. Signal voltage between connector C-91 terminals C5 and C6 will vary from about 0.4 at idle to about 4.6 volts at wide open throttle.
- The Engine Control Module (ECM) also receives this signal. This TPS is a variable resistance with one side (connector E-5 terminal 2) connected only to the ECM connector to have the 5 volts supply voltage. The other side (connector E-5 terminal 1) is connected to the Transmission Control Module (TCM) (floating ground) and the ECM (ground). The "middle" (the wiper) (connector E-5 terminal 3) is connected to the TCM and the ECM.
- The TCM monitors output voltage from the TPS and determines fuel delivery based on throttle valve angle (driver demand).
- This TPS is an electrical component and must not be soaked in any liquid cleaner or solvent, as damage may result.

DIAGNOSTIC AIDS:
- This Diagnostic is an electrical test done by the TCM.
- Detection conditions:
- Voltage between connector C-91 terminals C5 and C6 > 4.9 volts. This detection occurs when: The wiper is short to voltage (engine can stall) or open.
- The condition needs to be present for at least 0.5 seconds. Note: during the detection time the TCM reads "100% (wide open throttle)."
- Action after the detection time: BACKUP MODE.
- Recovery conditions: To recover when voltage < or = to 4.9 volts and do an IGNITION CYCLE.