Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

Use a test lamp in order to backprobe the brake switch connector C1 between terminal A and ground.

Does the test lamp light?

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Go to Step  2

Go to Step  3

1. Use the test lamp in order to backprobe the brake switch connector C1 between terminal B and ground.
2. Depress the brake pedal while observing the test lamp.

Does the test lamp light?

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Go to Step  4

Go to Step  5

Use the test lamp in order to backprobe the left IP junction block connector C3 between terminal A1 and ground.

Does the test lamp light?

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Go to Step  6

Go to Step  7

1. Use the test lamp in order to backprobe splice pack S301 between terminal E and ground.
2. Depress the brake pedal while observing the test lamp.

Does the test lamp light?

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Go to Step  8

Go to Step  9

1. Test the adjustment of the stoplamp switch.
2. If the brake switch adjustment is OK, replace the brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic brakes.

Is the repair complete?

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Go to Exterior Lights System Check

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Repair the open in CKT 140 between the left IP junction block and the brake switch. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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Replace the left IP junction block. Refer to Relay/Fuse Center Replacement in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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Repair the open in splice pack S301. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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Repair the open in CKT 20 between the brake switch and splice pack S301. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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