GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2007 🢒 Isuzu MD F-Series 🢒 Body Systems 🢒 Lighting 🢒 Stop Lamps Inoperative

Stop Lamps Inoperative Hydraulic Brakes

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Press down the brake pedal.

Do the stop lamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Disconnect the hazard flasher.
  2. Probe the brake switch input circuit at the hazard flasher connector with a test lamp that is connected to ground.
  3. Press down the brake pedal.

Does the test lamp illuminate?

Go to Step 7

Go to Step 4

4
  1. Disconnect the stop lamp switch.
  2. Probe the voltage input circuit of the stop lamp switch connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

5
  1. Connect a fused jumper wire between the voltage input circuit of the stop lamp switch connector and the voltage output circuit of the stop lamp switch connector.
  2. Probe the brake switch input circuit at the hazard flasher connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 6

6

Does the fuse in the jumper wire open?

Go to Step 11

Go to Step 12

7
  1. Connect a fused jumper wire between the brake switch input circuit of the hazard flasher connector and the LH rear lamp output circuit of the hazard flasher connector.
  2. Press down the brake pedal.

Does the left stop lamp illuminate?

Go to Step 9

Go to Step 13

8

Inspect for poor connections at the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 14

9

Inspect for poor connections at the hazard flasher. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 15

10

Repair the following in the voltage input circuit of the stop lamp switch:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

11

Repair a short to ground in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

12

Repair an open or high resistance in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

13

Repair an open or high resistance in the ground circuit of the stop lamps. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

14

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 16

--

15

Replace the hazard flasher.

Did you complete the replacement?

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

Stop Lamps Inoperative Air Brakes

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Press down the brake pedal.
  2. Apply the trailer hand brake.

Do the stop lamps illuminate for both actions?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Are the stop lamps inoperative from the trailer hand brake only?

Go to Step 9

Go to Step 4

4
  1. Disconnect the hazard flasher.
  2. Probe the brake switch input circuit at the hazard flasher connector with a test lamp that is connected to ground.
  3. Press down the brake pedal.

Does the test lamp illuminate?

Go to Step 8

Go to Step 5

5
  1. Disconnect the stop lamp switch.
  2. Probe the voltage input circuit of the stop lamp switch connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 15

6
  1. Connect a fused jumper wire between the voltage input circuit of the stop lamp switch connector and the brake switch input circuit of the stop lamp switch connector.
  2. Probe the brake switch input circuit at the hazard flasher connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 7

7

Does the fuse in the jumper wire open?

Go to Step 16

Go to Step 17

8
  1. Connect a fused jumper wire between the brake switch input circuit of the hazard flasher connector and the LH rear lamp output circuit of the hazard flasher connector.
  2. Press down the brake pedal.

Does the left stop lamp illuminate?

Go to Step 13

Go to Step 18

9
  1. Disconnect the trailer stop lamps switch.
  2. Probe the voltage input circuit of the trailer stop lamps switch connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 19

10

Connect a fused jumper wire between the voltage input circuit of the trailer stop lamps switch connector and the brake switch input circuit of the trailer stop lamps switch connector.

Do the stop lamps illuminate?

Go to Step 14

Go to Step 11

11

Does the fuse in the jumper wire open?

Go to Step 20

Go to Step 21

12

Inspect for poor connections at the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 25

Go to Step 22

13

Inspect for poor connections at the hazard flasher. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 25

Go to Step 23

14

Inspect for poor connections at the trailer stop lamps switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 25

Go to Step 24

15

Repair the following in the voltage input circuit of the stop lamp switch:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

16

Repair a short to ground in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

17

Repair an open or high resistance in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

18

Repair an open or high resistance in the ground circuit of the stop lamps. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

19

Repair the following in the voltage input circuit of the trailer stop lamps switch:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

20

Repair a short to ground in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

21

Repair an open or high resistance in the brake switch input circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 25

--

22

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 25

--

23

Replace the hazard flasher.

Did you complete the replacement?

Go to Step 25

--

24

Replace the trailer stop lamps switch. Refer to Trailer Stop Lamp Switch Replacement .

Did you complete the repair?

Go to Step 25

--

25

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3