GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Automatic Transmission Related Connector End Views in Automatic Transmission - 4L60-E/4L65-E

1

Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections?

--

Go to Step 2

Go to Exterior Lighting Systems Description and Operation

2

Verify that the backup lamps are inoperative.

Do the backup lamps operate normally?

--

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

Go to Step 3

3

Is only one backup lamp inoperative?

--

Go to Step 4

Go to Step 5

4

Inspect the inoperative bulb/socket for an open filament or open/corroded terminals and replace as necessary.

If a bulb/socket problem is not found, repair the open or high resistance in the backup lamp supply voltage circuit or ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

5

Inspect the TURN B/U fuse in the I/P fuse block.

Is the fuse open?

--

Go to Step 6

Go to Step 7

6

Disconnect the park/neutral position and backup lamp switch and use the J 39200 Digital Multimeter (DMM) to test for continuity to ground in the Ignition 1 Voltage circuit. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 10

Go to Step 11

7

Disconnect the harness from the park/neutral position and backup lamp switch and use the DMM to check the Ignition 1 voltage circuit at the connector for voltage. Refer to Circuit Testing in Wiring Systems.

Is voltage present?

B+

Go to Step 8

Go to Step 12

8

Reinstall the backup lamp bulbs and connect a fused jumper between the ignition 1 voltage circuit and the backup lamp supply voltage circuit at the park/neutral position and backup lamp switch connector.

Do the backup lamps illuminate?

--

Go to Step 15

Go to Step 9

9

Test the ground circuit at the inoperative backup lamp lamp socket. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 13

Go to Step 14

10

Repair the short to ground in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

11

Repair the short to ground in the backup lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

12

Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Repair the open or high resistance in the backup lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

14

Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

15

Adjust or replace the park/neutral position and backup lamp switch. Refer to Park/Neutral Position Switch Adjustment or Park/Neutral Position Switch Replacement in Automatic Transmission.

Did you complete the repair?

--

Go to Step 16

--

16

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3