GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Body Rear End Schematics

Connector End View Reference: Body Rear End Connector End Views , Computer/Integrating Systems Connector End Views in Computer/Integrating Systems, and Electrical Center Identification Views in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Verify that the hatch release is inoperative.

Does the hatch release operate normally?

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

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool command the liftgate lock motor to unlock.

Does the liftgate open?

Go to Step 5

Go to Step 4

4

  1. Probe the liftgate/endgate lock motor unlock control circuit of the body control module (BCM) harness connector C1 with a test lamp that is connected to a good ground.
  2. With a scan tool, command the liftgate lock motor to Unlock.

Does the test lamp illuminate?

Go to Step 7

Go to Step 8

5

  1. Disconnect the liftgate release switch.
  2. Probe the liftgate release switch signal circuit of the liftgate release switch harness connector with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 9

6

Connect a test lamp between the liftgate release switch signal circuit of the liftgate release switch harness connector and the ground circuit of the liftgate release switch harness connector.

Does the test lamp illuminate?

Go to Step 10

Go to Step 13

7

Test the liftgate/endgate lock motor lock control circuit for an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 11

8

Test the liftgate/endgate lock motor unlock control circuit for a short to ground or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 12

9

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

Did you find and correct the condition?

Go to Step 17

Go to Step 12

10

Inspect for poor connections at the harness connector of the liftgate release switch. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

11

Inspect for poor connections at the harness connector of the liftgate lock actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 15

12

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

13

Repair the open in the liftgate release switch ground circuit. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

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14

Replace the liftgate release switch.

Did you complete the replacement?

Go to Step 17

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15

Replace the liftgate lock actuator.

Did you complete the replacement?

Go to Step 17

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16

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 17

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17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step  2