GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

For Diagnostic Aids, refer to Testing for Intermittent Conditions and Poor Connections and Testing for Electrical Intermittents in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. The scan tool should read the normal state operation.

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe each door key cylinder unlock parameter in the driver door module (DDM) Inputs data list.

Does the scan tool display OFF?

Go to Step 3

Go to Step 7

3

  1. With the scan tool, observe each door key cylinder unlock parameter.
  2. Insert and rotate a key to the unlock position in each door key cylinder.

Does each door cylinder unlock parameter display ON as the key is rotated to the unlock position?

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

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the suspect door key cylinder unlock switch connector.
  3. Connect a 3-amp fused jumper wire between the suspect door key cylinder unlock switch connector signal circuit to the suspect door key cylinder unlock switch connector ground circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the suspect door key cylinder unlock parameter in the DDM inputs data list.

Does the scan tool display ON?

Go to Step 10

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the suspect door cylinder unlock switch connector.
  3. Connect a 3-amp fused jumper wire between the suspect door key cylinder unlock switch connector signal circuit and a good ground.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the suspect door key cylinder unlock parameter in the DDM inputs data list.

Does the scan tool display ON?

Go to Step 8

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Disconnect the suspect door key cylinder unlock switch connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the suspect door cylinder unlock parameter in the DDM inputs data list.

Does the scan tool display OFF?

Go to Step 10

Go to Step 7

7

Test the suspect door key cylinder unlock switch signal circuit for a short to voltage or an open circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

8

Test the suspect door key cylinder unlock switch ground circuit for a short to voltage or an open circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

9

Test the suspect door key cylinder unlock switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

10

Inspect for poor connections at the suspect door key cylinder unlock 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 14

Go to Step 12

11

Inspect for poor connections at the harness connector of the DDM. 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 14

Go to Step 13

12

Replace the suspect door key cylinder unlock switch. Refer to Door Lock Cylinder Replacement in Doors.

Did you complete the replacement?

Go to Step 14

--

13

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

Did you complete the replacement?

Go to Step 14

--

14

Operate the system to verify the repair.

Did you correct the condition?

System OK

Go to Step 2