For 1990-2009 cars

### Circuit Description

The engine control module (ECM) uses the ignition 1 voltage circuit to monitor system voltage. Voltage that is out of range will cause damage to components and incorrect input readings. If the ECM detects an excessively low system voltage, DTC P0562 will set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0562 System Voltage Low

### Conditions for Running the DTC

• | The ignition is ON with the engine OFF.

• | DTC P0562 runs continuously once the above condition is met.

### Conditions for Setting the DTC

The ECM detects a system voltage below 11 volts for more than 5 minutes.

### Action Taken When the DTC Sets

• | The control module stores the DTC information into memory when the diagnostic runs and fails.

• | The malfunction indicator lamp (MIL) will not illuminate.

• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

• | The driver information center, if equipped, may display a message.

### Conditions for Clearing the DTC

• | A current DTC Last Test Failed clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

• | Clear the DTC with a scan tool.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic References: Starting and Charging Schematics Connector End View References: Engine Electrical Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Start the engine.
2. Raise the engine speed above 1,500 RPM.
3. With a scan tool, observe the Ignition 1 voltage parameter in the engine control module (ECM) data list.

Is the voltage more than the specified value?

10.5 V

Go to Step 3

Go to Step 4

3 |

1. Observe the Freeze Frame/Failure Records data for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections

4 |

1. Measure the voltage at the battery with a DMM.
2. Raise the engine speed above 1,500 RPM.
3. Compare the voltage at the battery to the Ignition 1 voltage parameter in the ECM data list.

Is the battery voltage and Ignition 1 parameter readings different by more than the specified value?

0.5 V

Go to Step 5

Go to Charging System Test

5 | Test the ignition 1 voltage circuit of the ECM for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 6
6 | Test for an intermittent or poor connection at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7
7 | Replace the ECM. Did you complete the replacement? | -- | Go to Step 8 | --
8 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 9

9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK