GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Kodiak C-Series (Conventional) C6/C7/C8 🢒 Engine 🢒 Engine Controls - 7.8L 🢒 Diagnostic System Check - Engine Controls

Description

The Diagnostic System Check-Engine Controls is an organized approach to identifying a condition that is created by a malfunction in the electronic 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. Lack of communication may be because of a partial or a total malfunction of the class 2 serial data circuit. The specified procedure determines the particular condition.

  2. The presence of DTCs which begin with U, indicate that some other module is not communicating. Following the specified procedure will gather all the available information before you perform the tests. DTC U2104, U2106, and U2108 are CAN communications codes, and are not part of the class 2 Data Link system.

    3.

  3. If there are other modules with DTCs set, refer to the DTC list. The DTC list directs you to the appropriate diagnostic procedure.

    If the control module stores multiple powertrain DTCs, diagnose the DTCs in the following order:

    4. • Component level DTCs, such as sensor DTCs, solenoid DTCs, and relay DTCs. Diagnose the multiple DTCs within this category in numerical order. Begin with the lowest numbered DTC, unless the diagnostic table directs you otherwise.
    • System level DTCs, for example, misfire DTCs, fuel trim DTCs, and catalyst DTCs.

A Diagnostic System Check for Engine Controls

Step

Action

Yes

No

Important: 

   • DO NOT perform this diagnostic if there is not a driveability concern, unless another procedure directs you to this diagnostic.
   • Before you proceed with diagnosis, search for applicable service bulletins.
   • Unless a diagnostic procedure instructs you, DO NOT clear the DTCs.
   • If there is a condition with the starting system, refer to Diagnostic System Check - Engine Electrical in Engine Electrical.
   • Ensure the battery has a full charge.
   • Ensure the battery cables are clean and tight.
   • Ensure the ECM grounds are clean, tight, and in the correct location.

1

Install a scan tool.

Does the scan tool turn ON?

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 listed control modules. If you are using a Tech 2, obtain the information using the Class 2 Message Monitor feature:
    3. • The Chime/Radio
    • The electronic brake control module (EBCM)
    • The engine control module (ECM)
    • The instrument panel cluster (IPC)
    • The supplemental inflatable restraint (SIR)

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

Go to Step 3

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

3

Attempt to start the engine.

Does the engine start and idle?

Go to Step 4

Go to Engine Cranks but Does Not Run

4

Select the DTC display function for the following control modules:

    • The Chime/Radio module
    • The EBCM
    • The ECM
    • The IPC
    • The SIR

Does the scan tool display any DTCs?

Go to Step 5

Go to Step 10

5

With a scan tool, select Captured Info in order to store the powertrain DTC information.

Did you complete the action?

Go to Step 6

--

6

Does the scan tool display DTCs which begin with a U other than DTCs U2104, U2106, or U2108?

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

Go to Step 7

7

Does the scan tool display DTCs U2104, U2106, or U2108?

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

Go to Step 8

8

Does the scan tool display DTCs P0601, P0603, P0604, P0605, P0606, P1621?

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

Go to Step 9

9

Does the scan tool display DTCs P0562 or P0563?

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

Go to Diagnostic Trouble Code (DTC) List

10

Review the following symptoms:

    •  Hard Start
    •  Surges/Chuggles
    •  Cuts Out, Misses
    •  Poor Fuel Economy
    •  Excessive Smoke
    •  Idle Control Error
    •  Engine Does Not Stop

Refer to the applicable symptom diagnostic table.

Did you find and correct the condition?

System OK

Go to Intermittent Conditions