GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Use an ohmmeter to test continuity between terminal A5 (L-BU) of ISU connector and ground.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 3

Go to Step 2

2

Repair the open circuit between terminal A5 (L-BU) of the ISU connector and ground.

Is the repair complete?

--

System OK

--

3

  1. Disconnect the ISU connector.
  2. Connect a fused jumper wire to the positive battery terminal.
  3. Connect another jumper wire to ground.
  4. Apply the positive jumper wire to terminal D6 (GY) of the ISU connector.
  5. Apply the grounded jumper wire to terminal D5 (BN) of the ISU connector.
  6. Switch the jumper wires so that the positive jumper is connected to terminal D5 (BN) and the grounded jumper is connected to terminal D6 (GY).

Do the ISU when power and ground are applied to terminals D6 and D5 of the ISU connector?

Go to Step 5

Go to Step 4

4

Repair the open circuit between the ISU connector and S302.

Is the repair complete?

--

System OK

--

5

  1. Raise the power window in the driver's door.
  2. Disconnect the door lock connector at the top of the door lock. There are 3 connectors on the door lock. Use the schematic to verify the correct connector.
  3. Use an ohmmeter to measure the continuity between terminal A10 (BK) of the left door lock switch connector and ground.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 7

Go to Step 6

6

Repair the open circuit between the left door lock switch connector terminal A10 (BK) and ground.

Is the repair complete?

--

System OK

--

7

  1. Make sure that the ISU connector is connected.
  2. Touch a grounded jumper wire to terminal B4 (L-BU) of the disconnected left door lock switch connector.
  3. Remove the grounded jumper wire and touch it to terminal B5 (L-BU/WH) of the disconnected door left lock switch connector.

Do the doors lock and unlock when terminals B5 and B4 are alternately grounded?

0 ohms

Go to Step 8

Go to Step 9

8

  1. Make sure all the lock rods are connected to the driver's door lock.
  2. If no disconnected lock rods are located, replace the driver's door lock with the integral door lock switch. Do not confuse the door lock with the lock cylinder. The door lock has 3 connectors: the lock switch, the lock solenoid, and the door contact switch. Use the schematic to verify the correct connector.

Is the repair complete?

--

System OK

--

9

Use an ohmmeter to measure the continuity between terminal B4 (L-BU) of the disconnected left door lock switch connector and terminal A5 (L-BU) of the ISU connector.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 11

Go to Step 10

10

Repair the open L-BU wire.

Is the repair complete?

--

System OK

--

11

Use an ohmmeter to test the continuity between terminal B5 (L-BU/WH) of the disconnected left door lock switch connector and terminal A6 (L-BU/WH) of the ISU connector.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 13

Go to Step 12

12

Repair the open L-BU/WH wire.

Is the repair complete?

--

System OK

--

13

Replace the ISU.

Is the repair complete?

--

System OK

Go to Step 14

14

  1. Raise the power window in the driver's door.
  2. Disconnect the door lock connector at the top of the door lock. There are 3 connectors on the door lock. Use the schematic to verify the correct connector.
  3. Use an ohmmeter to measure continuity between terminal 6 (BK) of the right door lock switch connector and ground.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 16

Go to Step 15

15

Repair the open circuit between the right door lock switch connector terminal 6 (BK) and ground.

Is the repair complete?

--

System OK

--

16

  1. Make sure that the ISU connector is connected.
  2. Touch a grounded jumper wire to terminal 5 (L-BU) of the disconnected right door lock switch connector.
  3. Remove the grounded jumper wire and touch it to terminal 7 (L-BU/WH) of the disconnected right door lock switch connector.

Do the doors lock and unlock when terminals 7 and 5 are alternately grounded?

--

Go to Step 17

Go to Step 18

17

  1. Make sure all the lock rods are connected to the passenger's door lock.
  2. If no disconnected lock rods are located, replace the driver's door lock with the integral door lock switch. Do not confuse the door lock with the lock cylinder. The door lock has 3 connectors: the lock switch, the lock solenoid, and the door contact switch. Use the schematic to verify the correct connector.

Is the repair complete?

--

System OK

--

18

Use an ohmmeter to measure the continuity between terminal 5 (L-BU) of the disconnected right door lock switch connector and terminal A5 (L-BU) of the ISU connector.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 20

Go to Step 19

19

Repair the open L-BU wire.

Is the repair complete?

--

System OK

--

20

Use an ohmmeter to measure the continuity between terminal 7 (L-BU/WH) of the disconnected right door lock switch connector and terminal A6 (L-BU/WH) of the ISU connector.

Does the ohmmeter indicate the specified value?

--

System OK

--