1. Turn the ignition switch to the START position.
2. Observe the AUX BRK indicator lamp.

Does the indicator lamp light for four seconds after the engine is cranked?

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System OK

Go to Step 2

1. Remove the connector at the brake fluid flow switch.
2. Connect a J 39200 DMM between the switch terminals.
3. Start the engine.
4. Observe the test lamp.

Does the DMM indicate continuity?

--

Go to Step 3

Go to Step 4

Replace the flow switch. Refer to Fluid Flow Switch Replacement .

Is the repair complete?

--

System OK

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1. Connect a test lamp from CKT 1470 (RED) at the power brake booster pump motor relay to chassis ground.
2. Crank the engine.
3. Observe the test lamp. The test lamp will only light for four seconds.

Does the lamp light?

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Go to Step 5

Go to Step 6

1. Backprobe the multifunction alarm module with a digital multimeterJ 39200 from terminal A3 to chassis ground.
2. Measure the voltage while applying the service brakes.

Is the voltage more than the specification?

10.0 volts

Go to Step 7

Refer to Stop Lamps Inoperative in Lighting Systems

Replace the power brake booster pump motor relay. Refer to Power Brake Booster Replacement .

Is the repair complete?

--

System OK

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1. Remove the connector from the power brake booster pump motor.
2. Connect a J 39200 between the motor terminals.

Does the DMM indicate continuity?

--

Go to Step 8

Go to Step 11

1. Remove the connectors at the multifunction alarm module and the 9 way instrument panel harness connector.
2. Connect a J 39200 from the instrument panel harness connector C2 terminal 4 to CKT 484 (YEL/BLK) at the multifunction alarm module (terminal B3).

Does the DMM indicate continuity?

--

Go to Step 9

Go to Step 10

Replace the multifunction alarm module. Refer to Multifunction Alarm Module Replacement in Instrument Panels, Gauges and Console.

Is the repair complete?

--

System OK

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Repair the open in CKT 10 and CKT 484 (YEL/BLK) between the instrument panel harness connector and the multifunction alarm module.

Is the repair complete?

--

System OK

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Replace the power brake booster pump motor. Refer to Power Brake Booster Replacement .

Is the repair complete?

--

System OK

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