Engine Electrical

DTC P0562

Diagnostic Instructions

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

DTC Descriptor

DTC P0562
- System Voltage Low

Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) monitors the system voltage to ensure that the voltage stays within the proper range. Damage to components, and incorrect data may occur when the voltage is out of range.

Conditions for Running the DTC

* The vehicle speed is greater than 8 km/h (5 mph).
* The system voltage is between 9.5-18 volts.

Conditions for Setting the DTC

The ECM detects a system voltage less than 10 volts for 5 seconds.

Action Taken When the DTC Sets

* The ECM will command the charge indicator to be illuminated on the instrument panel cluster (IPC).
* The ECM will not illuminate the malfunction indicator lamp (MIL).
* The ECM will store conditions, which were present when the DTC set as Fail Records data only.

Conditions for Clearing the DTC

* The ECM will command the message OFF after one trip in which the diagnostic test has been run and passed.
* The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

Diagnostic Aids

* A low voltage DTC in multiple modules indicates a concern in the charging system.
* Inspect the ECM ground connection G106 (4.3L LU3) or G103 (all other engines) to insure that they are clean and tight.

Circuit/System Verification

1. Ignition On. Measure and record the voltage at the battery terminals. Verify that the battery voltage is 12-17 volts. Repeat with the engine running.

• If the battery voltage is not within the specified range, go to Charging System Test. Charging System Test

2. Engine running. Observe the Ignition 1 Signal parameter in the ECM scan tool data list. Verify that the scan tool displays a value that is within 1 volt of the battery voltage recorded in step 1.

• If the scan tool parameter is not within the specified range, go to Circuit/System Testing. Charging System Test

3. Go to Diagnostic Aids.

Circuit/System Testing

1. Ignition OFF. Disconnect the harness connector of the ECM.
2. Probe the ground circuits with a test lamp that is connected to B+. The test lamp should illuminate.

• If the test lamp does not illuminate, then test the ground circuit for an open/high resistance.

3. Test for 11-14 volts between the battery positive voltage and the ground circuits of the ECM.

• If not within the specified range, test the battery positive voltage circuits for a short to ground or an open/high resistance.

4. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests