GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The engine control module (ECM) continuously monitors the system voltage. The ECM monitors the system voltage to make sure that the voltage stays within the proper range. If the ECM detects an excessively high system voltage, DTC P0563 will set. A high voltage condition may cause a stalling condition or other driveability concerns.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0563 System Voltage High

Conditions for Running the DTC

    • The engine run time is more than 20 seconds.
    • Engine running above 1,200 RPM.
    • Vehicle speed above 8 km/h (5 mph).

Conditions for Setting the DTC

Ignition 1 voltage sensor is more than 2.0V.

Action Taken When the DTC Sets

    • The ECM stores DTC P0563 in the ECM memory when the diagnostic runs and fails.
    • The ECM will record the operating conditions at the time the diagnostic fails. The ECM stores this information in Failure Records.
    • The ECM disables most outputs.
    • The transmission defaults to a predetermined gear.
    • The torque converter clutch (TCC) operation is inhibited.
    • The instrument panel cluster (IPC) displays a message.
    • The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

    • The Conditions for Setting the DTC are no longer present.
    • A history DTC will clear after 40 malfunction free ignition cycles.
    • The ECM receives the clear code command from the scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Starting and Charging Schematics

Connector End View Reference: Engine Electrical Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF all the accessories.
  2. Measure the battery voltage at the battery using the DMM .
  3. Operate the engine speed above 2,000 RPM.

Is the battery voltage less than the specified value?

19 V

Go to Step 4

Go to Step 3

3

Replace the generator. Refer to Generator Replacement .

Is the action complete?

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Go to Step 5

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4

Replace the engine control module (ECM). Refer to Control Module References for replacement, setup, and programming.

Is the action complete?

--

Go to Step 5

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5

  1. Select the DTC option and the Clear DTC Information option using the scan tool.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the DTC reset?

--

Go to Step 2

System OK