GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0562 System Voltage Low

Object Number: 211077 Size: SF
Engine Controls Components
Cell 20: Power, Grounding, Generator and MIL
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 positive voltage terminals to the PCM. A system voltage DTC sets whenever the voltage is above or 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.
    • Use a scan tool to clear the DTCs.

Diagnostic Aids

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

An intermittent may be caused by any of the following conditions:

    • A poor connection
    • Rubbed through wire insulation
    • A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

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. Program the replacement PCM and perform the Crankshaft Position System Variation Learn Procedure. Refer to the latest Techline procedures for PCM programming.

    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

Value(s)

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?

1,400 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 J 39200 DMM.

Is the battery voltage more than the specified value?

1,400 RPM

12 V

Go to Step 4

Go to Powertrain Control Module Controlled Generator Diagnosis

4

  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connectors.
  3. Turn ON the ignition leaving the engine OFF.
  4. Measure the ignition voltage at the ignition positive voltage circuit #2 using a J 39200 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 poor connection at the PCM.
  3. Repair the connection as necessary. Refer to Connector 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 or high resistance in the ignition positive voltage circuit #2. Refer to Connector Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 8

--

7

  1. Turn OFF the ignition.
  2. Replace the PCM. Refer to the Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 8

--

8
  1. Using the scan tool, 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 the applicable DTC table

System OK