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 provide 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

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 volts

0 volts

12.5-14.5 volts

Circuit/System Description

The transmission control module (TCM) continuously monitors the system voltage on the ignition voltage and the battery voltage circuits. Lower than normal or higher than normal voltage may be inadequate to operate the transmission control solenoids properly. Improper solenoid operation may cause erratic transmission operation and tie-up conditions, which may result in internal damage.

Conditions for Running the DTC

DTC P0562

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

DTC P0563

The ignition is ON.

Conditions for Setting the DTC

DTC P0562

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

DTC P0563

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

Action Taken When the DTC Sets

DTC P0562 and P0563 are type C DTCs.

Conditions for Clearing the DTC

DTC P0562 and P0563 are type C DTCs.

Diagnostic Aids

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

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline 20-Way Connector End View
    •  Automatic Transmission Internal Connector End Views
    •  Automatic Transmission Related Connector End Views

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

Start the engine in PARK and observe the Ignition Voltage parameter on the scan tool. The Ignition Voltage should be between 12.0-14.5 volts.

Circuit/System Testing

  1. Start the engine and observe the Ignition Voltage parameter with a scan tool. The Ignition Voltage parameter should be between 12.0-14.5 volts.
  2. If the voltage is not within the specified range, refer to Charging System Test .
  3. Increase the engine speed to 1,500 RPM. The Ignition Voltage parameter should remain between 12.0-14.5 volts.
  4. If the voltage is not within the specified range when the engine speed is increased, refer to Charging System Test .
  5. Turn OFF the ignition. Disconnect the TCM connector. Probe the battery positive voltage and the ignition 1 voltage circuits of the TCM connector with the ground probe of the DMM. Connect the positive lead of the DMM to the battery positive terminal. Turn ON the ignition, with the engine OFF. Measure to voltage drop for each circuit. The voltage drop should be less than 0.5 volt.
  6. If the voltage drop is greater than 0.5 volt, repair the high resistance in the affected circuit.
  7. 4. Turn OFF the ignition. Using the positive probe of the DMM, probe the ground circuits of the TCM connector. Connect the negative lead of the DMM to the battery ground terminal. Observe and record the voltage measurements. The voltage drop should be less than 0.2 volt.
  8. If the voltage drop is greater than 0.2 volt, repair the open or high resistance in the affected circuit.
  9. If all circuits and connections test normal, replace the TCM.

Component Testing

Start the engine and raise the engine speed to 1,500 RPM. Observe the Ignition Voltage parameter on the scan tool. The Ignition Voltage should be between 12.0-14.5 volts.

If the voltage is not within the specified range, perform the Charging System Test .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for TCM replacement, setup, and programming