GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The transmission control Module (TCM) continuously monitors the system voltage on the ignition and battery circuits. Higher than normal voltages may cause the various solenoids with the transmission to operate improperly or damage solid state components within the TCM.

When the TCM detects a high voltage, DTC P0563 sets, which is a type 'C' DTC.

Conditions for Running the DTC

Ignition is switched on.

Conditions for Setting the DTC

The TCM detects that the system voltage is greater than 18 volts for 10 seconds.

Action Taken When the DTC Sets

    • The TCM does not request the powertrain interface module (PIM) to illuminate the check powertrain malfunction indicator lamp (MIL).
    • The TCM records the operating conditions when the 'Conditions for Setting the DTC' are met. The TCM records this information as a Failure Record.
    • The TCM stores DTC P0563 into TCM history.

Conditions for Clearing the DTC

Tech 2 can clear the DTC.

The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring.

Diagnostic Aids

  1. Using Tech 2, check other system control modules for voltage related DTCs. If other modules have voltage related DTCs logged, this would indicate that the fault is not in the TCM.
  2. Running the engine with a battery charger attached may cause DTC P0563 to set.
  3. Inspect the vehicle electrical system for any of the following conditions:
  4. • Inspect the charging system for high resistance or loose connections. These could cause an intermittent overcharging condition.
    • Check the vehicle battery for open or sulfated cells.

Test Description

The following number refers to the step number on the diagnostic table:

3. This step checks the generator output. For testing procedures, refer to Charging System Inoperative.

Step

Action

Values

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

For information on Testing Wiring Faults, refer to Wiring Systems.

1

Has the Diagnostic System Check - Automatic Transmission been completed?

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Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2

  1. Connect Tech 2 to the DLC
  2. Ignition ON, engine OFF
  3. Record any stored ECM and TCM DTCs.

Did you record any other system DTCs set?

--

Go to the applicable DTC chart

Go to Step 3

3

  1. Turn off ignition and disconnect Tech 2 from the DLC.
  2. Ensure that all electrical consumers are turned off.
  3. Start engine and run at approximately 2,000 rpm or greater. Turn headlamps on and heater fan to high speed.

Using a voltmeter, measure voltage between battery positive terminal and ground points X119_GP4 and X119_G4_GP3.

13.8-14.5 Volts

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn the ignition, head lamps and heater fan OFF.
  2. Disconnect the transmission wiring harness connector from the TCM.
  3. Using a digital voltmeter and a 21W test lamp connected in parallel, measure voltage between the transmission wiring harness TCM connector, terminal X1-9 (ignition voltage) and ground with ignition turned ON.
  4. Also, measure voltage between the transmission wiring harness TCM connector, terminal X1-27 (battery voltage) and ground with ignition turned ON.

Are voltage readings within the specified range?

--

Go to Step 5

Repair Charging System Refer to Engine Electrical

5

Replace TCM. Refer to Transmission Control Module Replacement.

Is the replacement complete?

--

Go to Step 6

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6

Perform the following operation to verify the repair:

  1. Select DTC on Tech 2
  2. Select 'Clear info'.
  3. Operate the vehicle in the Conditions for Running the DTC

Does the DTC reset?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK

7

Use Tech 2 to read DTC information.

Does Tech 2 display any DTCs that have not been diagnosed and rectified?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK

When all diagnosis and repairs are completed, clear all DTCs and verify correct operation.