Review the backup lamp operation and perform the necessary inspections.

Did you complete the system review and inspection?

--

Go to Step 2

Go to Symptoms

Attempt to operate the backup lamps.

Does the system operate normally?

--

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

Go to Step 3

1. Block the wheels and apply the park brake to prevent the vehicle from moving.
2. Turn the ignition ON with the engine off.
3. Place the transmission in the REVERSE position.
4. Remove the backup lamp and test for voltage at cavity B of the backup lamp socket.

Is battery voltage available at cavity B of the backup lamp socket?

B+

Go to Step 9

Go to Step 4

Test for voltage at cavity C of connector C1 of the backup lamp switch (park/neutral position switch).

Is battery voltage available at the backup lamp switch?

B+

Go to Step 6

Go to Step 5

1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Repair the open voltage supply circuit to the backup lamp switch CKT 139 (PNK).

Did you complete the repair?

--

Go to Step 10

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Connect a fused jumper wire with a 20A fuse at connector C1 of the backup lamp switch between terminals C and F.

Does the backup lamp turn on?

--

Go to Step 7

Go to Step 8

1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Replace or adjust the PNP switch. Refer to the following:

•	4L60E Park/Neutral Position Switch Replacement or Park/Neutral Position Switch Adjustment

•	4L80E Park/Neutral Position Switch Replacement or Park/Neutral Position Switch Adjustment

Did you complete the repair?

--

Go to Step 10

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1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Repair the open circuit between the backup lamp switch and the backup lamp CKT 24 (LT GRN).

Did you complete the repair?

--

Go to Step 10

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1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Repair the ground circuit for the backup lamp CKT 250 (BLK).

Did you complete the repair?

--

Go to Step 10

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Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3

Review the backup lamps operation and perform the necessary inspections.

Did you complete the system review and inspection?

--

Go to Step 2

Go to Symptoms

Attempt to operate the backup lamps.

Does the system operate normally?

--

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

Go to Step 3

1. Remove the inoperative back up lamp bulb and visually and physically inspect it.
2. Electrically test it if necessary to determine its condition.

Is the backup lamp bulb okay?

--

Go to Step 5

Go to Step 4

Replace the backup lamp bulb.

Did you complete the repair?

--

Go to Step 8

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1. Block the wheels and apply the park brake to prevent the vehicle from moving.
2. Turn the ignition ON with the engine off.
3. Place the transmission in the REVERSE position.
4. Remove the inoperative backup lamp and test for voltage at cavity A of the backup lamp socket.

Is battery voltage available at cavity A of the backup lamp socket?

B+

Go to Step 7

Go to Step 6

1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Repair the open circuit between the backup lamp switch and the backup lamp CKT 24 (LT GRN).

Did you complete the repair?

--

Go to Step 8

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1. Turn off the ignition.
2. Place the transmission in the PARK position.
3. Repair the ground circuit for the backup lamp CKT 150 (BLK).

Did you complete the repair?

--

Go to Step 8

--

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3