Circuit Test B - Main Power Relay
Enter this test only when directed here by other circuit tests. To prevent replacement of good components, check for faults in following non-EEC components:
- Ignition switch.
- Alternator.
- Battery cables, ground straps and voltage regulator.
This test is only intended to diagnose the following circuits and components:
- Vehicle wiring harness circuits (VPWR and GND).
- Main power relay.
CIRCUIT PIN IDENTIFICATION
| Circuit | Breakout Box Pin No. | PCM Pin | Wire Color | ||
|---|---|---|---|---|---|
| GND | 54 | C3-15 | Black/Orange | ||
| GND | 52 | C3-2 | Black/Orange | ||
| GND | 25 | C3-1 | Black/Lt. Green | ||
| GND | 17 | C1-20 | Black | ||
| GND (1) | 18 | C1-10 | Black | ||
| VPWR | 51 | C3-14 | Yellow/White | ||
| KVPWR | 55 | C3-5 | Blue/Red | ||
|
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- 1) Check VPWR To PCM Turn ignition off. Install breakout box (leave PCM disconnected). Turn ignition on. Measure voltage at breakout box test pin(s) VPWR. See CIRCUIT PIN IDENTIFICATION table. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, go to step 3).
- 2) Check Grounds At PCM Turn ignition off. Measure resistance between ground and breakout box test pin No. 25 (GND). If resistance is less than 5 ohms, VPWR circuit is okay. Return to test than sent you here. If resistance is greater than 5 ohms, repair GND circuit in question.
- 3) Check VPWR Wire From Main Relay To PCM Turn ignition off. Remove main power relay (located in fuse panel). Measure resistance between breakout box test pin VPWR and VPWR wire at main relay connector. See Fig 1 or Fig 2. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair VPWR wire.
- 4) Check Ground At Main Power Relay Measure resistance between ground and GND terminal at main power relay connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair GND circuit in question.
- 5) Check Battery Voltage At Main Power Relay Turn ignition on. Measure voltage at BATT terminal at main power relay connector. If voltage is 10 volts or greater, go to next step. If voltage is less than 10 volts, check 30-amp EGI INJ fuse. If fuse is okay, service BATT circuit.
- 6) Check PWR Circuit To Main Power Relay Measure voltage at PWR terminal at main power relay connector. If voltage is 10 volts or greater, replace main power relay. If voltage is less than 10 volts, check 10-amp ENGINE fuse. If fuse okay, service PWR circuit.