GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Backup Lights System Check?

--

Go to Step 2

Go to Backup Lamp System Check

2

Do the backup lamps not light (manual transmission)?

--

Go to Step 7

Go to Step 3

3

Do the backup lamps not light (automatic transmission)?

--

Go to Step 13

--

4

    • On 3-speed vehicles, disconnect the PNP switch connector C2.
    • On 4-speed vehicles, disconnect the transmission range switch.

Do the backup lamps remain lit?

--

Go to Step 5

Go to Step 6

5

    • On 3-speed vehicles, repair the short to voltage in the RED or BRN/RED wire between the PNP switch and the rear combination lamps. Refer to Wiring Repairs in Wiring Systems.
    • On 4-speed vehicles, repair the short to voltage in the RED or BRN/RED wire between the transmission range switch and the rear combination lamps. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

6

    • On 3-speed vehicles, replace the PNP switch.
    • On 4-speed vehicles, replace the transmission range switch.

Is the repair complete?

--

Go to Backup Lamp System Check

--

7

  1. Use a J 39200 in order to backprobe the backup lamp switch from terminal 1 to terminal 4 (switch side).
  2. Measure the resistance.

Is the resistance below the specified value?

0.3 ohms

Go to Step 8

Go to Step 20

8

Use a J 35616-200 unpowered test lamp in order to backprobe the backup lamp switch from cavity 1 to the chassis ground.

Does the test lamp light?

--

Go to Step 9

Go to Step 10

9

  1. Disconnect the connectors C402 and C406.
  2. Use a J 39200 in order to backprobe the backup lamp switch from the cavity 2 to C402/C406 cavity 6.
  3. Measure the resistance.

Is the resistance below the specified value?

0.3 ohms

Go to Step 11

Go to Step 12

10

Repair the open in the YEL wire between the fuse block 2 and the backup lamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

11

Repair the open in the BLK ground wire between C402/C406 and G300. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

12

Repair the open in the RED or BRN/RED wire between C402/C406 and the backup lamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

13

  1. On 3-speed transmissions, disconnect the park/neutral position (PNP) switch connector C2.
  2. Connect a J 39200 digital multimeter across the PNP switch connector C2 terminals 1 and 3 (switch side).
  3. On 4-speed models, disconnect the transmission range switch.
  4. Connect a J 39200 across the transmission range switch terminals 8 and 6.

Measure the resistance.

Is the resistance less than the specified value?

0.3 ohms

Go to Step 14

Go to Step 15

14

  1. Disconnect the connectors C402 and C406.
  2. On 3-speed vehicles, connect a J 39200 from PNP switch connector C2 cavity 3 to connector C402/C406 cavity 6.
  3. On 4-speed vehicles, connect a J 39200 across the transmission range switch cavity 6 to connector C402/C406 cavity 6.

Measure the resistance.

Is the resistance less than the specified value?

0.3 ohms

Go to Step 16

Go to Step 17

15

  1. Replace the PNP switch on 3-speed transmissions.
  2. Replace the transmission range switch on 4-speed transmissions. Refer to Transmission Range Switch Replacement in Transaxle/Transmission.

Is the repair complete?

--

Go to Backup Lamp System Check

--

16

  1. On 3-speed vehicles, connect a J 35616-200 unpowered test lamp from the PNP switch connector C2 cavity 1 to the chassis ground.
  2. On 4-speed vehicles, connect a J 35616-200 unpowered test lamp from the transmission range switch cavity 8 to the chassis ground.

Does the test lamp light?

--

Go to Step 18

Go to Step 19

17

Repair the open in the RED or BRN/RED wire between the PNP switch or the transmission range switch and S418. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

18

Repair the open in the BLK wire between S404 and G300. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

19

Repair the open in the YEL wire between the PNP switch or the transmission range switch and the fuse block 2. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Backup Lamp System Check

--

20

Replace the backup lamp switch.

Is the repair complete?

--

Go to Backup Lamp System Check

--