GM Service Manual Online
For 1990-2009 cars only

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Action

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No

Schematic Reference: Door Lock/Indicator Schematics

DEFINITION: This diagnostic table should be used to diagnose a complete failure of all the unlock functions.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Actuate each door lock switch, one at a time, to the unlock position.

Did the doors unlock from each switch?

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

Go to Step 3

3

Did the doors unlock from any switch?

Go to Power Door Locks Inoperative - One Door or Switch

Go to Step 4

4

  1. Install a scan tool.
  2. With a scan tool, command the doors to unlock.

Did the doors unlock?

Go to Step 5

Go to Step 6

5

  1. With a scan tool, observe the Passenger Door Unlock parameter.
  2. Actuate a door lock switch to the unlock position.

Does the Passenger Door Unlock parameter change state?

Go to Step 20

Go to Step 13

6

  1. Remove the door unlock relay.
  2. Connect a test lamp between the battery positive voltage circuit on the coil side of the door unlock relay at the fuse block and a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 18

7

Connect a test lamp between the battery positive voltage circuit on the switched side of the door unlock relay at the fuse block and a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 18

8

  1. Connect a test lamp between the door unlock control circuit of the door unlock relay at the fuse block and a good ground.
  2. With a scan tool, command the doors to unlock.

Did the test lamp illuminate?

Go to Step 9

Go to Step 14

9

  1. Remove the door lock relay.
  2. Connect a test lamp between the ground circuit on the switched side of the door lock relay at the fuse block and B+.

Does the test lamp illuminate?

Go to Step 10

Go to Step 19

10

  1. Install the door unlock relay.
  2. Connect a fused jumper between the switched side ground circuit and the load side of the door lock relay at the fuse block.
  3. With a scan tool, command the doors to unlock.

Did the doors unlock?

Go to Step 12

Go to Step 11

11

Inspect for poor connections at the door 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 21

Go to Step 16

12

Inspect for poor connections at the door lock 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 21

Go to Step 17

13

Test for an open in the door unlock control circuit between the body control module (BCM) and the door lock switches. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 15

14

Test for an open in the door lock control circuit between the BCM and the door unlock relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 15

15

Inspect for poor connections at the 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 21

Go to Step 20

16

Replace the door lock relay.

Did you complete the repair?

Go to Step 21

--

17

Replace the door unlock relay.

Did you complete the repair?

Go to Step 21

--

18

Repair the open in the door lock relay battery positive voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 21

--

19

Repair the open in the door lock relay ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 21

--

20

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

Did you complete the repair?

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2