Diagnostic Aids
Perform this test when directed by QUICK TEST procedure. This CIRCUIT TEST is intended to diagnose:
- Wiring harness circuit TP, VREF and SIGRTN.
| Circuit | PCM Pin No. | (1) BOB Pin No. | Wire Color | ||
|---|---|---|---|---|---|
| TP | 20 | 47 | Red | ||
| VREF | 37 | 26 | Brown | ||
| SIGRTN | 21 & 29 | 46 | White/Black | ||
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1) Check VREF Signal Turn ignition off. Disconnect TP sensor wiring harness connector. Turn ignition on. Measure voltage between VREF terminal of TP sensor harness connector and ground. If voltage is 4-5 volts, go to next step. If voltage is not 4-5 volts, go to CIRCUIT TEST VREF.
2) Check TP Sensor Turn ignition off. Leave TP sensor wiring harness connector disconnected. Connect ohmmeter test leads to SIGRTN and TP terminals of TP sensor. Measure resistance at following throttle positions and verify resistance is as indicated:
- Throttle closed: 1000 ohms.
- Throttle at 1/2 open: 1000-10,000 ohms.
- Throttle fully opened: about 10,000 ohms.
If resistance is as specified, go to next step. If resistance is not as specified, replace TP sensor.
3) Check TP & SIGRTN Circuits Turn ignition off. Leave TP wiring harness connector disconnected. Install Breakout Box (007-00033), leaving PCM disconnected. Measure resistance between SIGRTN test pin at breakout box and SIGRTN terminal of TP sensor harness connector. Measure resistance between TP test pin at breakout box and TP terminal of TP sensor harness connector. Resistance should be 5 ohms or less. Measure resistance between breakout box test pin No. 47 and ground. Resistance should be 10,000 ohms or more. If resistance is as specified, replace PCM. If resistance is not as specified, repair circuit.