GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0562 System Voltage Low

Object Number: 211077 Size: SF
Engine Controls Components
MIL, Generator, and Fuel Composition Sensor
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The powertrain control module (PCM) monitors the system voltage on the ignition feed terminals to the PCM. A system voltage DTC sets whenever the voltage is below a calibrated value.

Conditions for Running the DTC

The engine speed is more than 1300 RPM.

Conditions for Setting the DTC

The ignition voltage is less than 10 volts for 240 seconds.

Action Taken When the DTC Sets
    • The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers stores this information.
    • A history DTC is stored.

Conditions for Clearing the DTC
    • A history DTC clears after 40 consecutive warm up cycles without a fault.
    • The scan tool can clear the DTC.

Diagnostic Aids

Whenever a DTC sets when an accessory is operated, check for a poor connection or an excessive current draw.

Test Description

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

  1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data captured when this DTC set. The scan tool stores this data for later reference.

    2.

  2. This step checks if the generator is malfunctioning under load conditions.

    3.

  3. The PCM Controlled Generator Diagnosis will further check the PCMs control of the generator.

    4.

  4. This step checks the ignition positive voltage circuit #2 for any excessive resistance. An open circuit will cause a no start condition.

    5.

  5. Reprogram the replacement PCM and perform the Crankshaft Position System Variation Learn Procedure. Refer to the latest Techline procedures for PCM reprogramming.

    6.

  6. If no malfunctions are present at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Install a scan tool.
  2. Start the engine.
  3. Raise the engine speed to the specified value.
  4. Load the electrical system by turning ON the following items:
    5. • Headlights
    • High blower motor
    • Rear defroster

Is the ignition voltage less than the specified value?

1400 RPM

10 V

Go to Step 3

Go to Step 8

3

  1. Run the engine at the specified value.
  2. Measure the battery voltage at the battery using a DMM.

Is the battery voltage more than the specified value?

1400 RPM

12 V

Go to Step 4

Go to Charging System Test in Engine Electrical

4

  1. Turn OFF the ignition .
  2. Disconnect the PCM electrical connectors.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the ignition voltage at the ignition positive voltage circuit 439 using a DMM.

Is the ignition voltage more than the specified value?

10 V

Go to Step 5

Go to Step 6

5
  1. Turn OFF the ignition .
  2. Check for a malfunctioning terminal connection at the PCM.
  3. Repair the electrical connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 8

Go to Step 7

6
  1. Turn OFF the ignition .
  2. Repair the poor electrical connection (high resistance) in the ignition positive voltage circuit #2. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 8

--

7

  1. Turn OFF the ignition .

    2. Important: The replacement PCM must be programmed.

  2. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Idle the engine at the normal operating temperature.
  4. Operate the vehicle within the Conditions for Setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has Ran and Passed?

--

Go to Step 9

Go to Step 2

9

Check to see if any DTCs are set.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to applicable DTC table

System OK