GM Service Manual Online
For 1990-2009 cars only

Description

The Diagnostic System Check-Engine Controls is an organized approach to identifying a condition that is created by a malfunction in the engine control system. The Diagnostic System Check must be the starting point for any driveability concern. The Diagnostic System Check directs the service technician to the next logical step in order to diagnose the concern. Understanding and correctly using the diagnostic table reduces diagnostic time and prevents the replacement of good parts.

Test Description

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

  1. The Data Link References table is to identify which serial data protocol a particular control module is using. The powertrain control module (PCM) utilizes keyword serial data and controller area network (CAN) serial data.

  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

    • Ensure the battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.
    • Ensure the battery cables are clean and tight.
    • Search for applicable service bulletins.
    •  Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the symptom. Refer to Strategy Based Diagnosis in General Information.
    •  Ensure that the engine and control module grounds are clean, tight, and in the correct location.
    •  Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories in Wiring Systems.

Did you find and correct the condition?

System OK

Go to Step 2

2

  1. Install a scan tool.
  2. Turn ON the scan tool.

Does the scan tool turn ON?

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 establish communication with the listed control modules:
  3. •  Powertrain control module (PCM)
    • Body control module (BCM)
    • Electronic brake control module (EBCM)
    • Instrument panel cluster (IPC)

Does the scan tool communicate with all the listed control modules?

Go to Step 4

Go to Data Link References in Data Link Communications

4

Attempt to start the engine.

Does the engine crank?

Go to Step 5

Go to Symptoms - Engine Electrical in Engine Electrical

5

Did the engine start and idle?

Go to Step 6

Go to Engine Cranks but Does Not Run

6

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

  1. Select the DTC display function for the following control modules and record the DTCs:
  2. •  Powertrain control module (PCM)
    • Body control module (BCM)
    • Electronic brake control module (EBCM)
    • Instrument panel cluster (IPC)
  3. If multiple powertrain DTCs are stored, diagnose the DTCs in the following order:
  4. 2.1. Component level DTCs. For example, sensor DTCs, solenoid DTCs, and relay DTCs

    Begin with the lowest number DTC unless the diagnostic table directs you otherwise.

    2.2. System level DTCs. For example, misfire DTCs, EVAP system DTCs and fuel trim DTCs.
  5. If there are any powertrain DTCs, Select Capture Info in order to store the Powertrain DTC information with a scan tool.

Does the scan tool display any DTCs?

Go to Step 7

Go to Step 11

7

Does the scan tool display DTCs which begin with a "U" other than U0107?

Go to Data Link References in Data Link Communications

Go to Step 8

8

Does the scan tool display DTC U0107?

DTC U0107

Go to Step 9

9

Does the scan tool display DTC P0602, DTC P1621, or DTC P2610?

Go to DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610

Go to Step 10

10

Does the scan tool display DTCs P0562, P0563, P0621, or P0622?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List

11

Is the customer's concern with the automatic transmission - 5AT?

Go to Diagnostic System Check - Automatic Transmission in Automatic Transmission - 5AT

Go to Step 12

12

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

Go to Inspection/Maintenance (I/M) System Check

Go to Step 13

13

Are there any engine controls or driveability symptoms observed?

Go to Symptoms - Engine Controls

System OK