Did you perform the Lighting Systems Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Lighting Systems

Verify that the high mount stoplamp is inoperative.

Does the high mount stoplamp operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

1. Connect a test lamp between ground and the two test points of the VECHMSL 10A fuse in the Underhood Fuse Block. Refer to Circuit Testing in Wiring Systems.
2. Apply the service brakes.

Does the test lamp illuminate at any of the test points?

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Go to Step 5

Go to Step 4

Locate and repair the open, high resistance or short to ground in CKT 17 (WHT). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 10

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1. Disconnect the high mount stoplamp.
2. Connect a test lamp between ground and terminal A of the high mount stoplamp connector. Refer to Circuit Testing in Wiring Systems.
3. Apply the service brakes.

Does the test lamp illuminate?

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Go to Step 7

Go to Step 6

Locate and repair the open, high resistance, or short to ground in CKT 1320 (LT BLU). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 10

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1. Disconnect the high mount stoplamp.
2. Connect a test lamp between the connector terminal A and terminal B. Refer to Circuit Testing in Wiring Systems.
3. Apply the service brakes.

Does the test lamp illuminate?

B+

Go to Step 8

Go to Step 9

Replace the high mount stoplamp. Refer to High Mount Stop Lamp Replacement .

Is the repair complete?

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Go to Step 10

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Locate and repair the open or high resistance in CKT 1850 (BLK) or 1350 (BLK). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 10

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Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3