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For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2002 🢒 Isuzu T-Series (Truck Line C) 🢒 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.

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. This step stores the engine control module (ECM) diagnostic trouble code (DTC) information into the scan tools memory. After you complete the diagnostic procedure, review the captured information in order to catch the next DTC if the control module stores multiple DTCs. Review the Freeze Frame data and the Failure Records data. Use this information in order to determine how frequently and how recently the DTC set. This information may help diagnose an intermittent condition. Information about the operating conditions at the time that the DTC set may also help diagnose an intermittent condition. Capturing the stored information saves the data that the ECM loses during the following conditions:

    3. • When a diagnostic procedures instructs you to clear the DTCs.
    • When a diagnostic procedure instructs you to disconnect the ECM connectors.
    • When a diagnostic procedure instructs you to replace the ECM.

  3. 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.

    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 Symptoms - Engine Electrical in Engine Electrical.
   • Ensure that the battery has a full charge.
   • Ensure that the battery cables are clean and tight.
   • Ensure that 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 following control modules. If you are using a Tech 2, obtain the information using the Class 2 Message Monitor feature:
    3. • The engine control module (ECM)
    • The electronic brake control module (EBCM)

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

Go to Step 3

Go to Diagnostic Starting Point - Data Link Communications 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 modules:

    • The ECM
    • The EBCM

Does the scan tool display any DTCs?

Go to Step 5

Go to Symptoms - Engine Controls

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 DTC 0034 or 0035?

Go to DTC 0034 or DTC 0035

Go to Step 7

7

Review the following symptoms:

    •  Engine Hunting
    •  Engine Idle Speed High
    •  Idle Control Error
    •  Exhaust Brake Error
    •  Excessive Smoke

Refer to the applicable symptom diagnostic table.

Did you find and correct the condition?

System OK

Go to Symptoms - Engine Controls