GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 XLR 🢒 Accessories 🢒 Entertainment 🢒 Diagnostic System Check - Vehicle

Circuit Description

The ignition mode switch has two contact buttons.

    •  The bottom one has two indicators on it, O and ACC. This button cycles the ignition through the following modes:
       - OFF -- This is the normal state upon entering the vehicle, and can also be reached from any other mode by depressing the button. The O indicator illuminates.
       - Accessory -- This mode can be reached from the Off state by depressing the button. The ACC indicator illuminates.
       - ON with the engine OFF -- This state can be reached from the Off or Accessory modes by depressing the button for about 5-6 seconds. The upper LED illuminates.
    • The upper button, with a circle indicator on it, that starts the engine if brake pedal is applied.

Test Description

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

  1. Lack of communication may be due to a partial or a total malfunction of the GMLAN or Class 2 serial data circuit. The specified procedures will determine the particular condition.

  2. This step is for areas that have inspection and maintenance testing procedures for emissions testing. Use this step if the testing facility found one or more I/M system statuses that did not set.

Step

Action

Yes

No

1

Perform the following preliminary inspections:

  1. Ensure that the battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.
  2. Ensure that the battery cables are clean and tight.
  3. Inspect for any open fuses.
  4. Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the symptom.
  5. Ensure that the grounds are clean, tight, and in the correct location.
  6. Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories in Wiring Systems.
  7. Search for applicable service bulletins.

Did you find and correct the condition?

System OK

Go to Step 2

2

Install a scan tool.

Does the scan tool power up?

Go to Step 3

Go to Scan Tool Does Not Power Up in Computer/Integrating Systems

3

Turn ON the ignition, with the engine OFF.

Is the NO FOB DETECTED message displayed on the DIC?

Go to Key Fob Not Detected in Keyless Entry

Go to Step 4

4

Select Vehicle Control Systems, Computer/Integrating Systems and then Vehicle DTC Information on the scan tool.

Does the scan tool display No Comm. for any control module?

Go to Data Link References in Computer/Integrating Systems

Go to Step 5

5

Attempt to start the engine.

Does the engine crank over?

Go to Step 6

Go to Symptoms - Engine Electrical in Engine Electrical

6

Attempt to start the engine.

Does the engine start and idle?

Go to Step 7

Go to Engine Cranks but Does Not Run in Engine Controls - 4.6L (LH2)

7

Important: Do NOT clear the DTCs unless instructed by a diagnostic procedure.

  1. Diagnose the DTCs in the order that the DTCs appear on the scan tool or mis-diagnosis may occur.
  2. If multiple powertrain DTCs are stored, diagnose the DTCs in the following order:
    3. 2.1. Component level DTCs, such as sensor DTCs, solenoid DTCs, and relay DTCs.
    2.2.  System level DTCs, for example, misfire DTCs, EVAP system DTCs, and fuel trim DTCs.

Advance to the List All DTCs screen on the scan tool.

Does the scan tool display any DTCs?

Go to Step 8

Go to Step 9

8

If there are any powertrain DTCs, select Captured Info in order to store the powertrain DTC information with a scan tool.

Did you complete the action?

Go to Diagnostic Trouble Code (DTC) List - Vehicle for applicable diagnostic procedure

--

9

Is the customer concern with Inspection/Maintenance (I/M) testing?

Go to Inspection/Maintenance (I/M) System Check in Engine Controls - 4.6L (LH2)

Go to Symptoms - Vehicle