Chart C-2F, TPS Enrichment Check
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- TPS idle service specification is .2-.7 volt.
- "Scan" tester indicates actual TPS signal voltage received by ECM. If voltage drops low at any point while opening throttle, ensure it is not due to movement of the harness causing an intermittent. "Scan" tester only updates information from TPS each 1.25 seconds, so it may be necessary to backprobe ECM terminal No. 23 with a DVOM to locate an intermittent problem.
- Adjust TPS to specification. If TPS can not be adjusted, replace TPS.
- The 510,000-ohm resistor inside the ECM should cause the TPS signal to be high when the TPS is disconnected, unless circuit No. 417 is shorted to ground or ECM is faulty.
- This step distinguishes between a faulty TPS and a circuit problem causing loss of 5-volt reference to TPS.
- The 510,000-ohm resistor inside the ECM should cause the TPS signal to have 5 volts if the TPS is disconnected, unless circuit No. 417 is shorted to ground or the ECM is faulty. If ECM is putting 5 volts on circuit No. 417 but does not indicate an over 4.50 volt TPS signal on "Scan" tester, the ECM is faulty.