GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Body 🢒 Wiring Systems 🢒 Diagnostic System Check - Theft Deterrent

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the serial data circuit or due to a total malfunction of the serial data circuit. The specified procedure will determine the particular condition.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the intelligent switching unit (ISU).

Does the scan tool communicate with the ISU?

Go to Step 3

Go to Scan Tool Does Not Communicate with Component in Data Link Communications

3

Select the ISU display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Diagnostic Trouble Code (DTC) List in Body Control Systems

Go to Symptoms - Theft Deterrent