GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Body Rear End Schematics

1

Did you review the Access Panel Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Access Panel Description and Operation

2

  1. Press any of the access panel relaease butttons on the key fob.
  2. Operate the liftgate lock/unlock release switch.

Did the liftgate window release?

Go to Access Panel Description and Operation in Wiring Systems

Go to Step 3

3

  1. Remove the liftgate lock/unlock relay.
  2. Connect a test lamp between the liftgate lock/unlock relay switch circuit and a good ground.
  3. Operate the liftgate lock/unlock release switch.

Does the test lamp illuminate?

Go to Step 4

Go to Step 9

4

  1. Connect a fused jumper wire between the liftgate lock/unlock relay switch circuit and the liftgate release motor rear control circuit.
  2. Operate the liftgate lock/unlock release switch.

Does the liftgate window operate?

Go to Step 5

Go to Step 7

5

  1. Connect a test lamp between door lock motor unlock control circuit of the lift gate lock/unlock relay and a good ground.
  2. Operate any of the door unlock switches.

Does the test lamp illuminate?

Go to Step 6

Go to Access Panel Description and Operation in Doors

6

  1. Connect a test lamp between the door lock motor unlock control circuit of the liftgate lock/unlock relay and the liftgate lock/unlock relay ground.
  2. Operate any of the door unlock switches.

Does the test lamp illuminate?

Go to Step 11

Go to Access Panel Description and Operation in Doors

7

  1. Disconnect the liftgate release motor rear connector.
  2. Connect a test lamp between the liftgate release motor control circuit and a good ground.
  3. Operate the liftgate lock/unlock release switch.

Does the test lamp illuminate?

Go to Step 8

Go to Step 14

8

  1. Connect a test lamp between the liftgate release motor rear control circuit and the liftgate release motor rear ground circuit.
  2. Operate the liftgate lock/unlock release switch.

Does the test lamp illuminate?

Go to Step 12

Go to Step 16

9

  1. Disconnect the liftgate lock/unlock release switch connector.
  2. Connect a test lamp from the liftgate lock/unlock release switch battery positive voltage circuit and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 15

10

  1. Reconnect the liftgate lock/unlock relay.
  2. Connect a test lamp between the liftgate lock/unlock release switch battery positive voltage circuit and the switch circuit of the liftgate lock/unlock relay.

Does the test lamp illuminate?

Go to Step 17

Go to Step 13

11

Inspect for poor connections at liftgate lock/unlock relay. 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 20

Go to Step 18

12

Inspect for poor connections at the harness connector of the liftgate release motor. 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 20

Go to Step 189

13

Repair the open or high resistance in the switch circuit of the liftgate lock/unlock relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

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14

Repair the open or high resistance in the control circuit of the liftgate release motor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the replacement?

Go to Step 20

--

15

Repair the open or high resistance in the battery positive voltage circuit of the liftgate lock/unlock release switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the replacement?

Go to Step 20

--

16

Repair the open or high resistance in the ground circuit of the liftgate release motor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the replacement?

Go to Step 20

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17

Replace the liftgate lock/unlock release switch.

Did you complete the replacement?

Go to Step 20

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18

Replace the liftgate lock/unlock relay.

Did you complete the replacement?

Go to Step 20

--

19

Replace the liftgate release motor rear.

Did you complete the replacement?

Go to Step 20

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20

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2