GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Operate the turn signals.

Do the turn signal lamps and indicators operate properly?

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

Go to Step 3

3

Do the turn signal lamps remain illuminated but not flash when the turn signal switch is placed in the TURN LEFT or TURN RIGHT position?

Go to Step 11

Go to Step 4

4

Are only the turn signal indicators inoperative?

Go to Step 10

Go to Step 5

5

Are all of the turn signal lamps and indicators inoperative?

Go to Step 6

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Disconnect the turn signal flasher.
  3. Connect a test lamp between the ignition 3 voltage circuit of the turn signal flasher and a good ground.
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 7

Go to Step 12

7

  1. Turn OFF the ignition.
  2. Connect a test lamp between the ignition 3 voltage circuit of the turn signal flasher and the ground circuit of the turn signal flasher.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 8

Go to Step 23

8

  1. Turn OFF the ignition.
  2. Connect a 20 amp fused jumper between the ignition 3 voltage circuit of the turn signal flasher and the signal circuit of the turn signal flasher.
  3. Disconnect the turn/hazard switch.
  4. Connect a test lamp between the turn signal flasher signal circuit and a good ground.
  5. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 21

Go to Step 14

9

  1. Turn OFF the ignition.
  2. Disconnect the turn/hazard switch.
  3. Connect a 20 amp fused jumper between the turn signal flasher signal circuit and the supply voltage circuit of the appropriate turn signal lamp.
  4. Turn ON the ignition, with the engine OFF.
  5. Place the turn signal switch in the appropriate position.

Does the turn signal lamp illuminate?

Go to Step 21

Go to Step 15

10

  1. Place the turn signal switch in the appropriate position.
  2. Observe the appropriate Turn Signal Indicator parameter in the Instrument Cluster inputs data list.

Does the scan tool indicate that the Turn Signal Indicator parameter turns ON and OFF when the turn signal switch is placed in the appropriate position?

Go to Step 19

Go to Step 16

11

Test for a short to voltage in the turn signal flasher signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 18

12

Test for an open or short to ground in the ignition 3 voltage circuit of the turn signal flasher. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 13

13

Test for a short to ground in the turn signal flasher signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 22

14

Test for an open or high resistance in the turn signal flasher signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 18

15

Test for an open or high resistance in the appropriate turn signal lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 17

16

Test for an open or high resistance in the appropriate turn signal lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 19

17

Test for an open or high resistance in the ground circuit of the appropriate turn signal lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 20

18

Inspect for poor connections at the turn signal flasher. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 27

19

Inspect for poor connections at the instrument cluster. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 26

20

Inspect for poor connections at the inoperative turn signal lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 24

21

Inspect for poor connections at the turn/hazard switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 25

22

Repair a short to ground in the supply voltage circuit of the turn signal lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

23

Repair an open or high resistance in the ground circuit of the turn signal flasher. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

24

Replace the inoperative turn signal lamp. Refer to Park/Turn Signal Lamp Bulb Replacement or Tail Lamp Replacement .

Did you complete the replacement?

Go to Step 28

--

25

Replace the turn/hazard switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 28

--

26

Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

Go to Step 28

--

27

Replace the turn signal flasher. Refer to Turn Signal Flasher Replacement .

Did you complete the replacement?

Go to Step 28

--

28

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2