Chart A5 - TPS Enrichment Check
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This step checks that fully depressing TPS will cause an ECM "Rich" command. Normal response is for Code 21 to be set. On some vehicles this will cause a low dwell (full rich) on others it will not.
- This step distinguishes between a faulty TPS or ECM harness/ECM. Code 21 would normally be set provided engine RPM is not set above specifications.
- This step checks for 5 volt reference at TPS.
- This step checks for a grounded circuit. Normal circuit should read about 5 volts. Checking, for grounded TPS output to terminal No. 5 of ECM or short in wiring to terminals No. 5 and 8 from TPS, indicates whether fault is in wiring or ECM. A voltmeter with 10-megaohm resistance must be used for an accurate reading.