GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 DeVille 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Turn Signal Lamps and/or Indicators Inoperative

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. This step verifies that there is only one inoperative turn signal lamp. If not, the entire left or right side is inoperative.

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

Are only the turn signal indicators inoperative?

Go to Step 7

Go to Step 4

4

Are all of the turn signal lamps and indicators inoperative?

Go to Step 8

Go to Step 5

5

Is there only one inoperative turn signal lamp?

Go to Step 6

Go to Step 18

6

Is the inoperative lamp a rear turn signal lamp?

Go to Step 12

Go to Step 11

7
  1. Place the turn signal switch in the appropriate position.
  2. With a scan tool, observe the appropriate Turn Signal parameter in the Instrument Cluster (IPC) inputs data list.

Does the scan tool indicate that the Turn Signal parameter is ON?

Go to Step 22

Go to Step 17

8
  1. Turn OFF the ignition.
  2. Disconnect the turn/hazard flasher module.
  3. Turn ON the ignition, with the engine OFF.
  4. Place the turn signal switch in the LEFT TURN position.
  5. Connect a test lamp between the left turn signal circuit and a good ground.
  6. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 26

9

Connect a test lamp between the battery positive voltage circuit of the turn/hazard flasher module and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 24

10

Connect a test lamp between the battery positive voltage circuit of the turn/hazard flasher module and the ground circuit of the turn/hazard flasher module .

Does the test lamp illuminate?

Go to Step 20

Go to Step 25

11
  1. Turn OFF the ignition.
  2. Disconnect the inoperative turn signal lamp.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the supply voltage circuit of the inoperative turn signal lamp and a good ground.
  5. Place the turn signal switch in the appropriate position.

Does the test lamp flash ON and OFF?

Go to Step 13

Go to Step 16

12
  1. Turn OFF the ignition.
  2. Disconnect the inoperative turn signal lamp.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the supply voltage circuit of the inoperative turn signal lamp and a good ground.
  5. Place the turn signal switch in the appropriate position.

Does the test lamp flash ON and OFF?

Go to Step 14

Go to Step 16

13

Connect a test lamp between the supply voltage circuit of the inoperative turn signal lamp and the ground circuit of the inoperative turn signal lamp.

Does the test lamp flash ON and OFF?

Go to Step 23

Go to Step 27

14

Connect a test lamp between the supply voltage circuit of the inoperative turn signal lamp and the ground circuit of the inoperative turn signal lamp.

Does the test lamp flash ON and OFF?

Go to Step 15

Go to Step 27

15

Connect a test lamp between the outage detection signal circuit of the inoperative turn signal lamp and the ground circuit of the inoperative turn signal lamp.

Does the test lamp flash ON and OFF?

Go to Step 23

Go to Step 19

16

Test for an open or short to ground in the supply voltage circuit of the inoperative turn signal lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 20

17

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

Did you find and correct the condition?

Go to Step 32

Go to Step 22

18

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

Did you find and correct the condition?

Go to Step 32

Go to Step 21

19

Test for an open or high resistance in the outage detection signal 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 32

Go to Step 20

20

Inspect for poor connections at the harness connector of the turn/hazard flasher module. 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 32

Go to Step 28

21

Inspect for poor connections at the turn signal 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 32

Go to Step 29

22

Inspect for poor connections at the Instrument Cluster (IPC). 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 32

Go to Step 30

23

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 32

Go to Step 31

24

Repair an open or short to ground in the battery positive voltage circuit of the turn/hazard flasher module . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

25

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

Did you complete the repair?

Go to Step 32

--

26

Repair an open or short to ground in the ignition 1 voltage circuit of the turn signal switch . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

27

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

Did you complete the repair?

Go to Step 32

--

28

Replace the turn/hazard flasher module. Refer to Hazard and Turn Signal Flasher Replacement .

Did you complete the replacement?

Go to Step 32

--

29

Replace the turn signal switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 32

--

30

Replace the Instrument Cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Did you complete the replacement?

Go to Step 32

--

31

Replace the inoperative turn signal lamp. Refer to one of the following replacements:

    •  Tail Lamp Replacement

Did you complete the replacement?

Go to Step 32

--

32

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2