DTC 21

Fig. 029 Code 21 Throttle Position Sensor (TPS):

Fig. 030a Code 22 Throttle Position Sensor (TPS):

CODE 21


THROTTLE POSITION SENSOR (TPS)

(SIGNAL VOLTAGE HIGH)

2.0L (VIN 1)

FUEL INJECTION (TBI)

Circuit Description: The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle valve. Signal voltage will vary from less than 1.25 volts at idle to about 5 volts at wide open throttle (WOT).
The TPS signal is one of the most important inputs used by the ECM for fuel control and for many of the ECM controlled outputs.

Test Description: Numbers below refer to circled numbers on Diagnostic Charts.

1. This step checks to see if Code 21 is the result of a hard failure or an intermittent condition.
A Code 21 will set if:
TPS reading above 2.5 volts.
MAP reading below 55 kPa.
All of the above conditions present for 5 seconds.

2. This step simulates conditions for a Code 22. If the ECM recognizes the change of state, the ECM and CKTs 474 and 417 are OK.

3. This step isolates a faulty sensor, ECM, or an open CKT 452

Diagnostic Aids:

A "Scan" tool displays throttle position in volts. Closed throttle voltage should be less than 1.25V. TPS voltage should increase at a steady rate as throttle is moved to WOT.
A Code 21 will result if CKT 452 is open or CKT 417 shorted to voltage. If Code 21 is intermittent, refer to DIAGNOSIS BY SYMPTOM.