GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 8.1L 🢒 Diagnostic System Check - Engine Electrical

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 class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

    2.

  2. The symptom list in Symptoms will determine the correct diagnostic procedure to use.

    3.

  3. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Step

Action

Yes

No

1

Did you perform the Battery Inspection/Test?

Go to Step 2

Refer to Battery Inspection/Test

2

Install a scan tool.

Does the scan tool power up?

Go to Step 3

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

3

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to communicate with each module on the class 2 serial data circuit.
    3. • The body control module (BCM)
    • The driver information center (DIC)
    • The instrument panel cluster (IPC)
    • The powertrain control module (PCM)

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 4

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

4

  1. Select the Display DTCs function for each module. If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules have DTCs set.
  2. Record all of the displayed DTCs the DTC status and the module which set the DTC.

Does the scan tool display any DTCs?

Go to Step 5

Refer to Symptoms - Engine Electrical

5

Does the scan tool display any DTC beginning with "U"?

Go to Diagnostic Trouble Code (DTC) List in Data Link Communications

Go to Diagnostic Trouble Code (DTC) List