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Makes 🢒 Chevrolet 🢒 2001 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Transmission/Transaxle 🢒 Manual Transmission - NV 4500 🢒 Diagnostic System Check - Manual Transmission

Diagnostic System Check - Manual Transmission Diesel

Refer to Engine Controls Schematics in Engine Controls - 6.5 L.

Circuit Description

The Powertrain On-Board Diagnostic (OBD) System Check is an organized approach in identifying a problem created by an electronic engine system fault. The OBD System Check is the starting point for any driveability diagnosis. The OBD System Check directs the service technician to the next step in diagnosing the complaint. Do not perform this check if no driveability complaint exists. Understanding the table correctly reduces the diagnostic time. Understanding the table correctly prevents the replacement of good parts.

Diagnostic Aids

Important: Do not clear the DTCs unless directed by a diagnostic procedure. Clearing the DTCs will also clear valuable freeze frame and failure records data.

Inspect all related wiring and connections including the connections at the PCM. These may cause an intermittent malfunction.

Inspect any circuitry that is suspected of causing an intermittent problem for the following conditions:

    • Backed out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Poor terminal to wiring connections
    • Physical damage to the wiring harness
    • Corrosion

Test Description

The numbers below refer to the step number in the diagnostic table.

  1. This step will inspect for power and grounds to the data link connector (DLC).

    2.

  2. This step will determine if other modules on the Class 2 circuit can communicate, if no communication occurs, the class 2 circuit is grounded, open, shorted to voltage or the module is causing a communication problem.

    3.

  3. This step will inspect for DTCs associated with the Vehicle Theft Deterrent (VTD) which will prevent the vehicle from starting.

    4.

  4. Whenever multiple DTCs are stored, refer to the DTCs in the following order:

    5. 1. PCM Error DTCs
    2. System voltage DTCs
    3. Component level DTCs that indicate a malfunctioning part
    4. System level DTCs that indicate a system fault

  5. Inspecting the sensors for proper operation during warm up can be a crucial step in correctly diagnosing any driveability concern. Careful observation of these sensors during the engine warm up may reveal a slow responding sensor or a sensor that malfunctions only within a small portion of its range.

    After the engine is at the normal operating temperature, a comparison of the actual control system data with the typical values is a quick way to determine if any parameter is not within limits. A base engine condition, such as advanced cam timing, may substantially alter sensor values.

    Observe the engine coolant temperature (ECT) sensor for initial coolant temperature reading at ambient. Then observe the rise in the temperature while the engine is warming up.

Step

Action

Yes

No

1

    Important: 

       • Look for applicable service bulletins before proceeding with this diagnosis.
       • Do not turn OFF the ignition when performing this diagnostic.

  1. Connect the scan tool to the data link connector (DLC).
  2. Turn ON the ignition with the engine OFF.

Does the scan tool power-up?

Go to Step 2

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

2
  1. Install the scan tool.
  2. Turn ON the ignition.
  3. Attempt to establish communications with the PCM.

Does the scan tool display PCM data?

Go to Step 3

Go to Step 4

3

Does the engine start and continue to run?

Go to Step 6

Go to Step 5

4

Attempt to establish communications with other systems connected to the same serial data line, such as Passlock/EVO, ATC, ABS controllers.

Does scan tool communicate with the other systems?

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

Go to Diagnostic Starting Point - Data Link Communications in Data Link Communications

5

Inspect for PCM DTCs using the scan tool.

Were any last test failed, history, or MIL request DTCs set?

Go to applicable DTC table

Go to Engine Cranks but Does Not Run in Engine Controls - 6.5 L

6

Is DTC P0215, P1626 or DTC P1631 stored?

Go to applicable DTC table

Go to Step 7

7

  1. Turn ON the ignition with the engine OFF.
  2. Inspect the ECT.
  3. Start the engine.
  4. Allow the engine temperature to reach operating temperature.
  5. While the engine is reaching the operating temperature, observe the ECT.
  6. Compare the scan tool values of the sensors with the typical values shown in the Scan Tool Values.

Are the displayed values normal or within typical ranges?

Go to Symptoms - Engine Controls in Engine Controls - 6.5 L

Go to Diagnostic Aids and Test Description

Diagnostic System Check - Manual Transmission Gas

Description

The Diagnostic System Check 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. This step stores the PCM DTC information in the scan tool 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 PCM 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 PCM connectors.
    • When a diagnostic procedure instructs you to replace the PCM.

  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.

  4. 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:

    5. • 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.

  5. 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.

A Diagnostic System Check for Engine Controls

Step

Action

Yes

No

1

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 PCM grounds are clean, tight, and in the correct location.

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. • PCM
    • IP Cluster
    • EBCM

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 in Engine Controls - 8.1 L

4

Select the DTC display function for the following control modules:

    • PCM
    • IP Cluster
    • EBCM

Does the scan tool display any DTCs?

Go to Step 5

Go to Step 9

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"?

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 DTC P0601, P0602, P0604 or P0606?

Go to DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610 in Engine Controls - 8.1 L

Go to Step 8

8

Does the scan tool display DTC P0562, P0563, P1637, or P1638?

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

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 8.1 L

9

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

Go to Inspection Maintenance

Go to Step 10

10
  1. Review the following symptoms.
  2. Refer to the applicable symptom diagnostic table.
    3. •  Hard Start in Engine Controls - 8.1 L
    •  Surges/Chuggles in Engine Controls - 8.1 L
    •  Lack of Power, Sluggishness, or Sponginess in Engine Controls - 8.1 L
    •  Detonation/Spark Knock in Engine Controls - 8.1 L
    •  Hesitation, Sag, Stumble in Engine Controls - 8.1 L
    •  Cuts Out, Misses in Engine Controls - 8.1 L
    •  Poor Fuel Economy in Engine Controls - 8.1 L
    •  Poor Fuel Fill Quality in Engine Controls - 8.1 L
    •  Rough, Unstable, or Incorrect Idle and Stalling in Engine Controls - 8.1 L
    •  Dieseling, Run-On in Engine Controls - 8.1 L
    •  Backfire in Engine Controls - 8.1 L

Did you find and correct the condition?

System OK

Go to Intermittent Conditions in Engine Controls - 8.1 L