GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

Definition: The CTD Alarm is always ON.

1

Did you perform the Theft Deterrent Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

Disconnect the intelligent switching unit (ISU).

Does the alarm turn off?

Go to Step 5

Go to Step 3

3

  1. Disconnect the theft deterrent alarm.
  2. Test for a short to ground in the alarm ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 4

4

Test for a poor connection at the theft deterrent alarm. 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 8

Go to Step 7

5

Test for a poor connection at the ISU. 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 8

Go to Step 6

6

Important:  Perform the program procedure for the ISU.

Replace the ISU. Refer to Intelligent Switching Unit Replacement in Body Control Systems.

Did you complete the replacement?

Go to Step 8

--

7

Replace the theft deterrent alarm. Refer to Theft Deterrent Alarm Replacement .

Did you complete the replacement?

Go to Step 8

--

8

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2