GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Did you perform A Diagnostic System Check - Body Rear End?

Go to Step 2

Go to Diagnostic System Check - Body Rear End

2

Operate the rear wiper/washer and endgate/liftgate window release switch.

Does the endgate window release?

Go to Step 3

Go to Step 6

3

Operate the liftgate/endgate lock cylinder switch.

Does the endgate window release?

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

Go to Step 4

4

  1. Disconnect the liftgate/endgate lock cylinder switch.
  2. Connect a test lamp between the liftgate/endgate lock cylinder switch and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 23

5

  1. Connect the liftgate lock cylinder switch.
  2. Disconnect the door lock cylinder switch, LH.
  3. Connect a test lamp between the door lock cylinder switch and a good ground.
  4. Operate the liftgate lock cylinder switch.

Does the test lamp illuminate?

Go to Step 13

Go to Step 14

6

  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.
  3. With a scan tool monitor the liftgate window release switch input.
  4. Operate the liftgate window release switch.

Does the parameter change states?

Go to Step 9

Go to Step 7

7

  1. Disconnect the liftgate window release switch.
  2. Connect a fused jumper between the liftgate window release switch signal circuit and a good ground.

Does the scan tool parameter change states?

Go to Step 8

Go to Step 15

8

Connect a fused jumper between the liftgate window release switch signal circuit and the liftgate window release switch ground circuit.

Does the scan tool parameter change states?

Go to Step 17

Go to Step 24

9

  1. Remove the liftglass relay.
  2. Connect a test lamp between the liftglass relay battery positive and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 25

10

Connect a fused jumper between the liftglass relay battery positive and the liftgate window release actuator signal circuit.

Does the liftglass release?

Go to Step 16

Go to Step 11

11

  1. Disconnect the liftgate window release actuator.
  2. Connect a test lamp between the liftgate window release actuator signal circuit and a good ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 26

12

Connect a test lamp between the liftgate window release actuator signal circuit and the liftgate window release actuator ground circuit.

Does the test lamp illuminate?

Go to Step 21

Go to Step 27

13

Test the door lock cylinder switch, LH control circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 22

14

Test the liftgate lock cylinder switch control circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 20

15

Test the liftgate window release switch signal circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 18

16

Test the relay control circuit for a high resistance or and open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 28

17

Inspect for poor connections at the harness connector of the liftgate window release 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 34

Go to Step 19

18

Inspect for poor connections at the harness connector of the body control module (BCM). 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 34

Go to Step 29

19

Inspect for poor connections at the harness connector of the liftgate window release 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 34

Go to Step 30

20

Inspect for poor connections at the harness connector of the liftgate lock cylinder 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 34

Go to Step 31

21

Inspect for poor connections at the harness connector of the liftgate window release actuator. 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 34

Go to Step 32

22

Inspect for poor connections at the harness connector of the door lock cylinder switch, LH. 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 34

Go to Step 33

23

Repair the battery positive voltage circuit of the liftgate lock cylinder switch. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

--

24

Repair the ground circuit of the liftgate lock cylinder switch. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

--

25

Repair the battery positive voltage circuit of the liftglass relay. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

--

26

Repair the signal circuit of the liftgate window release actuator. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

--

27

Repair the ground circuit of the liftgate window release actuator. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

--

28

Replace the liftglass relay.

Did you complete the replacement?

Go to Step 34

--

29

Important: When replacing the body control module (BCM) refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the (BCM). Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 34

--

30

Replace the liftgate window release switch.

Did you complete the replacement?

Go to Step 34

--

31

Replace the liftgate lock cylinder switch. Refer to Endgate Lock Cylinder Replacement or Liftgate Lock Cylinder Replacement .

Did you complete the replacement?

Go to Step 34

--

32

Replace the liftgate window release actuator. Refer to Rear Compartment Lid Lock Actuator Replacement .

Did you complete the replacement?

Go to Step 34

--

33

Replace the door lock cylinder switch, LH.

Did you complete the replacement?

Go to Step 34

--

34

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2