Chart C2F - TPS Enrichment Check
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This test 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). Code 21 should normally be set.
- This step distinguishes between a faulty TPS, ECM or ECM harness. Code 21 should normally be set if engine RPM is not set above specifications.
- This tests for 5-volt reference signal at TPS. It should be about 5 volts. If loss of voltage reference were in ECM, it should set codes 21, 32 and 34, since it is the same 5 volt reference to MAP, BARO or VAC sensors. Therefore it must be an open in wiring.
- This tests 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 megaohm resistance must be used for an accurate reading.