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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Transmission/Transaxle 🢒 Automatic Transmission - ZF 4HP 16 🢒 Diagnostic System Check - Automatic Transmission

Circuit Description

The Diagnostic System Check - Automatic Transmission is an organized approach to identify a condition created by an automatic transmission. The Diagnostic System Check is the diagnostic starting point for an automatic transmission concern. The Diagnostic System Check directs you to the next logical step for diagnosing a transmission concern. Perform this check only if there is a driveability concern or if you have been directed here from another service information section. Follow the table to help reduce diagnostic time and help prevent unnecessary replacement of good parts.

Diagnostic Aids

Important: 

   • Do not clear the diagnostic trouble code (DTC) unless directed by a diagnostic procedure. Clearing the DTC will erase all Freeze Frame and Failure Records stored in ECM memory.
   • Poor engine performance can sometimes be diagnosed as a transmission driveability condition. In order to avoid misdiagnosis of the automatic transmission, always perform Diagnostic System Check - Engine Controls in Engine Controls-2.0L or Diagnostic System Check - Engine Controls in Engine Controls-2.5L.

    • Use a scan tool that is known to function correctly. If necessary, test the scan tool on another vehicle.
    • Ensure the scan tool contains the most current file available.
    • The scan tool will display a loss of communication error message under the following conditions:
       - The ECM power is interrupted.
       - The ignition switch is turned OFF.
       - The battery voltage level is very low.
       - A poor connection at the diagnostic link connector (DLC).

Test Description

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

  1. This step determines if the scan tool is receiving power through the DLC connector.

    2.

  2. This step determines if the ECM is transmitting serial data to the DLC and that the serial data circuit is not open or shorted.

    3.

  3. This step determines is an ECM DTC is current or stored in history.

    4.

  4. This step determines if the TCM is transmitting serial data to the DLC and that the serial data circuit is not open or shorted.

    5.

  5. This step determines if an ECM DTC is current or stored in history.

Step

Action

Yes

No

1

  1. Install a scan tool.

    2. Important: 

       • Inspect for applicable service bulletins before proceeding with this test. Perform this test only if there is a driveability complaint or if you have been directed to this table from another section in the service information.
       • Do not turn the ignition OFF when performing this diagnostic procedure. Do not clear the DTCs unless instructed by this diagnostic procedure.

  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

Attempt to establish communication with the ECM.

Does the scan tool communicate with the ECM?

Go to Step 4

Go to Scan Tool Does Not Communicate with Component in Data Link Communications

3

Select the ECM. Display DTCs function on the scan tool.

Does the scan tool display any ECM DTCs?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls-2.0L or Diagnostic Trouble Code (DTC) List in Engine Controls-2.5L

Go to Step 4

4

Attempt to establish communication with the TCM.

Does the scan tool communicate with the TCM?

Go to Step 5

Go to Scan Tool Does Not Communicate with Component in Data Link Communications

5

Select the TCM. Display DTCs function on the scan tool.

Does the scan tool display any TCM DTCs?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Symptoms - Automatic Transmission