Circuit Test B - Pcm Relay
Enter this test only when directed here by other circuit tests. To prevent replacement of good components, check for faults in following components:
- Ignition switch.
- Generator.
- Battery cables, ground straps and voltage regulator.
CIRCUIT PIN IDENTIFICATION
| Circuit | Breakout Box Pin No. | PCM Pin No. | Wire Color |
|---|---|---|---|
| GND | 4 | 4 | White/Green |
| GND | 10 | 10 | Black |
| GND | 19 | 19 | Black |
| GND | 43 | 43 | Black/Red |
| GND | 73 | 76 | Black |
| GND | 80 | 82 | Black |
| GND | 87 | 88 | Black |
| GND | 25 | 39 | Black/Red |
| VPWR | 51 | 56 | Black/White |
| VPWR | 57 | 61 | Black/White |
| VPWR | 81 | 83 | Black/White |
This circuit test is only intended to diagnose the following components and circuits:
- Harness circuits; VPWR and ground.
- PCM relay.
- 1) Check VPWR To PCM
Turn ignition off. Install breakout box and connect PCM. Turn ignition on. Measure voltage between ground and breakout box test pins No. 51, 57 and 81. If voltage is less than 10 volts, go to next step. If voltage is greater than 10 volts, go to step 7). If sent here from switch monitor test and voltage is greater than 10 volts, go to next step. - 2) Check VPWR Wire From PCM Relay To PCM
Turn ignition off. Install breakout box (leave PCM disconnected). Remove PCM relay located in engine compartment junction box. Measure resistance between Black/White wire at PCM relay harness connector and breakout box test pins No. 51, 57 and 81. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair VPWR (Black/White) wire. - 3) Check Battery Voltage At PCM Relay
Turn ignition off. Remove PCM relay. Measure voltage at PWR terminal (Red wire) at PCM relay connector. If voltage is 10 volts or greater, go to next step. If voltage is less than 10 volts, check 10-amp ENG CONT fuse. If fuse is not the problem, power distribution circuit. - 4) Check PWR Circuit To PCM Relay
Turn ignition off. Remove PCM relay located in fuse panel. Turn ignition on. Measure voltage at PWR terminal (Red wire) and ground terminal (White/Green wire) at PCM relay connector. If voltage is 10 volts or greater, go to step 6). If voltage is less than 10 volts, go to next step. - 5) Check Ground At PCM Relay
Turn ignition off. Remove PCM relay. Measure resistance between breakout box test pin No. 4 and GND (White Green wire) terminal at PCM relay. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open GND circuit. - 6) Test PCM Relay
Turn ignition off. Install breakout box (connect PCM). Disconnect PCM relay. Apply battery power to PCM relay terminal No. 1, and ground terminal No. 2. See Fig 2. With battery power applied, measure resistance between relay terminals No. 3 and 5. If resistance is less than 5 ohms with battery voltage applied, go to next step. If resistance is greater than 5 ohms with battery voltage applied, replace relay. - 7) Check Grounds At PCM
Leave ignition off. Install breakout box. (connect PCM). Measure resistance between ground and breakout box test pins No. 10, 19, 25, 43, 73, 80 and 87. If all resistance measurements are less than 5 ohms, ground circuits are okay, replace PCM. If any resistance measurement is greater than 5 ohms, repair GND circuit in question.