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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Sonoma Pickup - 4WD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Headlamps Inoperative - High Beams

Headlamps Inoperative - High Beams Standard

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight System Check?

--

Go to Step 2

Go to Headlight System Check

2

Use the scan tool in order to read the body control module (BCM) current trouble codes.

Is DTC B2575, B2577, or B2600 set as a current code?

--

Go to Diagnostic System Check - Body Control System in Body Control System

Go to Step 3

3

Does the HIGH BEAM telltale illuminate?

--

Go to Step 4

Go to Step 6

4

Inspect the connections at the UBEC. Perform any repairs as necessary.

Did you perform any repairs?

--

Go to Headlight System Check

Go to Step 5

5

Replace the UBEC.

Is the repair complete?

--

Go to Headlight System Check

--

6
  1. Place the headlamp switch in the HEAD position.
  2. Connect a test lamp from CKT 524 (PPL), pin E11 at the multifunction switch (C211) to ground.

Does the test lamp light?

--

Go to Step 7

Go to Step 8

7

Replace the multifunction switch.

Is the repair complete?

--

Go to Headlight System Check

--

8

Locate and repair the open in CKT 524 (PPL) between the following components:

    • The UBEC
    • The multifunction switch

Is the repair complete?

--

Go to Headlight System Check

--

Headlamps Inoperative - High Beams Envoy

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight System Check?

--

Go to Step 2

Go to Headlight System Check

2

Inspect the BCM for DTCs.

Were any DTCs set?

--

Go to Diagnostic System Check - Body Control System in Body Control System

Go to Step 3

3

Connect a test lamp between the following components:

    • Ground
    • The HIGH BEAM fuse in the underhood bussed electrical center (UBEC)

Does the test lamp light?

--

Go to Step 7

Go to Step 4

4

Does the test lamp light at one of the test points?

--

Go to Step 5

Go to Step 6

5

Locate and repair a short to ground in one of the following components:

    • CKT 3640 (ORN), in the high beam relay
    • CKT 1346 (LT BLU), between the high beam relay and the UBEC

Is the repair complete?

--

Go to Headlight System Check

--

6

Locate and repair the power source to the HIGH BEAM fuse. Refer to Power Distribution Schematics in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

7
  1. Disconnect the high beam relay.
  2. Connect a fused jumper at the high beam relay socket between the following components:
    3. • Cavity 30
    • Cavity 87

Do the high beams turn on?

--

Go to Step 11

Go to Step 8

8

Test CKT 3640 (ORN)/CKT 1346 (LT BLU) for an open.

Is an open present?

--

Go to Step 10

Go to Step 9

9

Repair the open in CKT 3640 (ORN)/ CKT 1346 (LT BLU).

Is the repair complete?

--

Go to Headlight System Check

--

10

Replace the UBEC.

Is the repair complete?

--

Go to Headlight System Check

--

11
  1. Connect a test lamp between the following components:
    2. • CKT 352 (WHT), cavity 85 at the high beam relay
    • CKT 1969 (BLK/WHT), cavity 86
  2. Turn the ignition switch to the RUN position.
  3. Place the multifunction switch in the HIGH BEAM position.

Does the test lamp light?

--

Go to Step 19

Go to Step 12

12

Verify that the HIGH BEAM telltale illuminates.

Does the telltale illuminate?

--

Go to Step 13

Go to Step 20

13
  1. Turn the ignition switch to the OFF position.
  2. Test CKT 1969 (BLK/WHT) to the high beam relay for an open.

Is an open present?

--

Go to Step 14

Go to Step 15

14

Repair the open in CKT 1969.

Is the repair complete?

--

Go to Headlight System Check

--

15

Test CKT 1969 (BLK/WHT) to the BCM cavity X for an open.

Is an open present?

--

Go to Step 14

Go to Step 16

16
  1. Turn the ignition switch to the RUN position.
  2. Test CKT 352 (WHT) at the BCM connector C3 cavity A8 for voltage.

Is voltage present?

--

Go to Step 17

Go to Step 18

17

Repair the open in CKT 352 (WHT).

Is the repair complete?

--

Go to Headlight System Check

--

18

Replace the BCM.

Is the repair complete?

--

Go to Headlight System Check

--

19

Replace the high beam relay.

Is the repair complete?

--

Go to Headlight System Check

--

20
  1. Reinstall the high beam relay.
  2. Use a fused jumper in order to backprobe between the following components:
    3. • CKT 1969 (BLK/WHT), cavity E11 at connector C211
    • Ground

Do the high beams turn on?

--

Go to Step 22

Go to Step 21

21

Locate and repair an open in CKT 1969 (BLK/WHT) and S287.

Is the repair complete?

--

Go to Headlight System Check

--

22
  1. Use a fused jumper in order to backprobe between the following components:
    2. • CKT 1850 (BLK), cavity E13 at connector C211
    • Ground
  2. Place the multifunction switch in the HIGH BEAM position.

Do the high beams turn on?

--

Go to Step 23

Go to Step 24

23

Locate and repair an open in CKT 1850 (BLK).

Is the repair complete?

--

Go to Headlight System Check

--

24

Inspect the steering column wiring for open circuits. Perform any repairs as necessary.

Did you perform any repairs?

--

Go to Headlight System Check

Go to Step 25

25

Replace the high beam switch.

Is the repair complete?

--

Go to Headlight System Check

--