B150 1/2 Ton Van V6-239 3.9L (1989)
Power Door Lock Relay: Testing and Inspection
To test the relay, move either of the door switches to the lock and unlock positions. An audible clicking sound should be heard from under the dash near
the steering column support. If the sound is heard while operating one switch but not the other, a defective switch or wiring may be at fault. Next, locate
the relay under the dash panel and test as follows:
1- Check for power by back probing the RD wire at the relay. If no power is present, check the circuit breaker and the wire between the relay and the
circuit breaker.
2- If power is present, back probe the OR/DG wire at the relay and move the switch to the lock position. Battery voltage should be present, indicating
that the relay operates in the lock position.
3- If power is not present, backprobe the OR wire and move the lock knob to the lock position. If power is not present at the OR wire, the door switch
may be defective.
4- If power is present at the OR/DG wire, back probe the PK/DB wire at the relay and move the lock knob to the unlock position. Battery voltage should
be present, indicating that the relay operates in the unlock position.
5- If power is not present at the PK/DB wire, backprobe the PK wire and move the lock knob to the unlock position. If power is not present at the PK
wire, the door switch may be defective.
6- Insure that the relay is properly grounded through the housing. This is the ground point for the entire power door lock system.
START
To test the relay, move either of the front lock knobs to the lock and unlock positions. An audible clicking sound should be heard from under the dash
near the steering column support. If the sound is heard while operating one knob but not the other, a defective switch or wiring may be at fault. If a
clicking sound is not heard, locate the relay and test as follows:
1. Check for power by back probing the RD wire at the relay.
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If power is present, go to step 2.
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If power is not present, check the circuit breaker and the wire between the relay and the circuit breaker.
2. Back probe the OR/DG wire at the relay and move the lock knob to the lock position. Battery voltage should be momentarily present, indicating
that the relay operates in the lock position.
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If power is present, go to step 4.
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If power is not present, go to step 3.
3. Backprobe the OR wire and move the lock knob to the lock position.
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If power is present, the relay is defective.
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If power is not present, the door switch or wiring may be defective.
4. Backprobe the PK/DB wire at the relay and move the lock knob to the unlock position. Battery voltage should be momentarily present, indicating
that the relay operates in the unlock position.
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If power is present, the relay is operating properly.
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If power is not present, go to step 5.
5. Backprobe the PK wire and move the lock knob to the unlock position.
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If power is present, the relay is defective.
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If power is not present, the door switch or wiring may be defective.
