GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0562:  System Voltage Low

DTC P0563:  System Voltage High

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Voltage

P2534

P2534

--

P0562, P0563

Ignition 0 Voltage

--

--

--

P0562, P0563

Battery Positive Voltage

--

--

--

P0562, P0563

Typical Scan Tool Data

System Voltage Parameter Data

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running in Park, normal operating temperature

Parameter Normal Range: 12.5-14.5 volts

Ignition Voltage

0 V

0 V

12.5-14.5 V

Circuit/System Description

The transmission control module (TCM) continuously monitors the system voltage on the ignition voltage circuit.

Conditions for Running the DTC

P0562

The engine speed is 1,200 RPM or greater for 5 seconds.

P0563

The ignition is ON.

Conditions for Setting the DTC

P0562

The TCM detects system voltage is 11 volts or less for 10 seconds.

P0563

The TCM detects system voltage is 18 volts or greater for 10 seconds.

Action Taken When the DTC Sets

DTCs P0562 and P0563 are type C DTCs.

Conditions for Clearing the DTC

DTCs P0562 and P0563 are type C DTCs.

Diagnostic Aids

  1. Observe the driver information center (DIC) messaging that would indicate the electrical system requires service.
  2. Inspect for loose or damaged terminals at the generator.
  3. Inspect for loose or worn generator drive belt.
  4. Use the scan tool in order to inspect all other modules for voltage related DTCs.
  5. Running the engine with a battery charger attached may cause DTC P0563 to set.
  6. Inspect the charging circuit for high resistance.
  7. Inspect the vehicle battery for open or sulfated cells.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12 and 14.5 volts.
  2. If not within the specified range, refer to Charging System Test .
  3. Observe the scan tool TCM Ignition Voltage parameter. The reading should be between 12 and 14.5 volts.

Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the TCM.
  2. Test for less than 10 ohm between the ground circuit terminal 49 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 32 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  6. Verify that a test lamp illuminates between the ignition circuit terminals listed below and ground:
  7. • Terminal 11
    • Terminal 31
    If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  8. If all circuits test normal, replace the TCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for TCM replacement, setup, and programming.