Throttle Position Sensor: Testing and Inspection

Fig. 049 - Chart C-2F TPS Enrichment Check:

CHART C-2F, TPS ENRICHMENT CHECK

1. This step checks that the TPS will cause an ECM "Rich" command when fully depressed manually. On some cars, this will cause a low dwell (full rich). On others it will not.

Code 21 should normally be set.

2. This step distinguishes between a faulty TPS or ECM harness/ECM.

Code 21 should normally be set, if engine RPM is not set above specifications.

3. This step checks for 5V. ref. at TPS. It should be about 5 volts. If loss of V. Ref. were in the ECM,it should set Codes 21, 32 and 34 since this is the same 5V to MAP, BARO or Vacuum Sensors. Therefore, it must be an open in the wire.

4. This step checks for a grounded circuit. Normal circuit should read about 5 volts. Checking for grounded TPS output to Terminal "2" of ECM,or short in wiring to Terminals "2" and "22" from TPS, indicates whether fault is in wiring or ECM. A voltmeter with a 10 megohms resistance must be used for an accurate reading.