GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 4WD 🢒 DTC 🢒 DTC P0562 System Voltage Low

Object Number: 211077 Size: SF
Engine Controls Components
MIL and Generator
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 1,300 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

If the DTC sets when an accessory is operated, inspect for a poor connection or an excessive current draw.

Test Description

The numbers below refers to the step numbers on the diagnostic table:

  1. This step tests if the generator is malfunctioning under load conditions.

    2.

  2. The PCM Controlled Generator Diagnosis will further test the PCMs control of the generator.

    3.

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

    4.

  4. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

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. Start the engine.
  2. Raise the engine speed to the specified value.
  3. Load the electrical system by turning on the following items:
    4. • Headlamps
    • Blower motor on high
    • Rear defroster
  4. With the scan tool, observe the ignition voltage.

Does the ignition voltage read less than the specified value?

1,400 RPM

10 V

Go to Step 3

Go to Diagnostic Aids

3
  1. Run the engine at the specified value.
  2. Measure the battery voltage at the battery using a DMM.

Does the battery voltage measure 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 connectors.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the ignition voltage at the ignition positive voltage circuit #2 using a DMM.

Does the ignition voltage measure more than the specified value?

10 V

Go to Step 5

Go to Step 6

5
  1. Turn OFF the ignition.
  2. Inspect for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 7

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

Did you complete the repair?

--

Go to Step 8

--

7

Important:: The replacement PCM must be programmed.

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

Did you complete the replacement?

--

Go to Step 8

--

8
  1. Use a scan tool to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK