GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 Engine 🢒 Engine Electrical 🢒 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 GMLAN circuit or due to a total malfunction of the class 2 serial data circuit or GMLAN 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 collect all the available information before you perform tests.

Step

Action

Yes

No

1

Perform the Battery Inspection/Test. Refer to Battery Inspection/Test .

Does the battery pass the test?

Go to Step 2

--

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

Does the scan tool power up?

Go to Step 3

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

3

Important:  The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.

  1. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
  2. Rotate the ignition switch through all positions while observing the Class 2 Power Mode parameter.

Does the ignition switch parameter reading match the ignition switch position for all switch positions?

Go to Step 4

Go to Power Mode Mismatch in Body Control System

4

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to communicate with each of the following modules on the class 2 serial data circuit or GMLAN circuit:
    3. • Amplifier (AMP)
    • Dash Integration Module (DIM)
    • Drivers Door Module (DIM)
    • Engine Control Module (ECM) (LA3, LY9)
    • Engine Control Module (ECM) ( LY7)
    • Heads Up Display (HUD)
    • Instrument Panel Cluster (IPC)
    • Instrument Panel Module (IPM)
    • Memory Seat Module
    • Navigation Display Head (NDH)
    • Navigation Module (NAV)
    • Navigation Radio (NRC)
    • OnStar (ONS)
    • Radio Module (IRC)
    • Remote Function Actuator (RFA)
    • Rear Integration Module (RIM)
    • Powertrain Control Module (PCM) (LS6)
    • Supplemental Inflatable Restraint (SIR)
    • Tilt Telescope Module (TTM)
    • Vehicle Theft Deterrent (VTD)

Does the scan tool communicate with all modules on the class 2 serial data circuit?

Go to Step 5

Go to Data Link References in Data Link Communications

5

  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 6

Go to Symptoms - Engine Electrical

6

Does the scan tool display any DTCs which begin with a "U"?

Go to Data Link References in Data Link Communications

Go to Step 7

7

Does the scan tool display DTC B1000, B1004, B1007 or B1009?

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

Go to Diagnostic Trouble Code (DTC) List