GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Backup Lamps Inoperative

Step

Action

Value(s)

Yes

No

1

Was the Backup Lights System Check performed?

--

Go to Step 2

Refer to Backup Lamp System Check

2

Inspect the VEH B/U fuse in the underhood fuse block.

Is the fuse open?

--

Go to Step 3

Go to Step 6

3
  1. Install a new VEH B/U fuse.
  2. Disconnect connector C402.
  3. Remove the right backup lamp bulb.
  4. Use a J 39200 (DMM) in order to probe connector C402 terminal A in the harness connector (underhood fuse block side) to ground.

Is the resistance less than the specified value?

2 ohms

Go to Step 4

Go to Step 5

4

Locate and repair the short to ground in CKT 1324 (LT GRN) in one of the following areas:

    • Underhood fuse block connector C1, terminal B1 to S304
    • S304 to the Automatic Day/Night Mirror circuit
        Refer to Automatic Day-Night Mirrors Schematics in Stationary Windows.
    • S304 to connector C402 terminal A.
    • S304 to connector C403 terminal A.

Is the repair complete?

--

Refer to Backup Lamp System Check

--

5

Important: Inspect the backup lamp bulb for a shorted filament that may cause a short to ground.

Locate and repair a short to ground in CKT 1324 (LT GRN) between connector C402 terminal A and the right backup lamp.

Is the repair complete?

--

Refer to Backup Lamp System Check

--

6

Inspect the B/U LP fuse in the underhood fuse block.

Is the fuse open?

--

Go to Step 7

Go to Step 10

7
  1. Install a new B/U LP fuse.
  2. Disconnect the harness from the backup lamp switch (M/T), or the park neutral position (PNP) switch (A/T).
  3. Use the J 39200 DMM in order to probe the connector terminal for CKT 839 (PNK) to ground.

Is continuity present?

--

Go to Step 8

Go to Step 9

8

Locate and repair the short to ground in CKT 839 (PNK).

Is the repair complete?

--

Refer to Backup Lamp System Check

--

9

Locate and repair the short to ground in CKT 1524 (GRY).

Is the repair complete?

--

Refer to Backup Lamp System Check

--

10
  1. Disconnect the harness from the backup lamp switch (M/T), or the park/neutral position switch (A/T).
  2. Turn the ignition switch to the RUN position.
  3. Use the J 39200 (DMM) in order to probe the connector terminal for CKT 839 (PNK) to ground.

Does the J 39200 (DMM) display the specified value?

B+

Go to Step 12

Go to Step 11

11

Locate and repair the open in CKT 839 (PNK).

Is the repair complete?

--

Refer to Backup Lamp System Check

--

12

Connect a fused jumper between the backup lamp switch (M/T), or the park/neutral position switch (A/T) connector terminals for CKT 839 (PNK) and CKT 1524 (GRY).

Do the backup lamps light?

--

Go to Step 13

Go to Step 14

13

Replace the backup lamp switch (M/T), or the park/neutral position switch (A/T).

Is the repair complete?

--

Refer to Backup Lamp System Check

--

14
  1. Turn the ignition switch to the RUN position.
  2. Shift the transmission to the REVERSE position.
  3. Use the J 39200 (DMM) in order to probe the VEH B/U fuse in the underhood fuse block to ground.

Does the J 39200 (DMM) display the specified value?

B+

Go to Step 16

Go to Step 15

15

Locate and repair the open in CKT 1524 (GRY).

Is the repair complete?

--

Refer to Backup Lamp System Check

--

16
  1. Replace the VEH B/U fuse if necessary.
  2. Remove one of the backup lamps from the socket.
  3. Use the J 39200 (DMM) in order to probe the backup lamp socket terminal A to ground.

Does the J 39200 (DMM) display the specified value?

B+

Go to Step 17

Go to Step 18

17

Locate and repair the open in CKT 1350 (BLK) between S427 and G450.

Is the repair complete?

--

Refer to Backup Lamp System Check

--

18

Locate and repair the open in CKT 1324 (LT GRN) between the underhood fuse block connector C1, terminal B1 and S304.

Is the repair complete?

--

Refer to Backup Lamp System Check

--