Circuit Description
The powertrain control module (PCM) continuously monitors the system voltage. The system voltage information is taken from the ignition feed circuit to the PCM. Voltages below 8.0 volts or above 17.1 volts cause improper system operation and/or component damage. The PCM operates in a default mode if a PCM voltage DTC sets. If the system voltage is low, the PCM raises the idle speed to increase the generator output. The PCM disables most outputs to protect the hardware, if the system voltage is high. The scan tool will not display data if system voltage is outside this range. Use a DMM to monitor the system voltage to check if the fault is currently present. DTC P0563 is a type 'C' DTC.
Conditions for Running the DTC
| • | Engine speed above 1,500 RPM. |
| • | Vehicle speed is above 8 km/h (5 mph). |
Conditions for Setting the DTC
The PCM detects a system voltage above 18 volts for more than 5 seconds.
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM will disable most outputs. |
| • | The transmission will default to third gear. |
| • | The PCM will inhibit torque converter clutch (TCC) operation. |
| • | The PCM will cycle the cooling fans ON and OFF every few seconds during the time the condition is present. |
| • | The PCM records the operating conditions at the time the diagnostic fails. |
| • | The PCM stores this information in the Failure Records. |
| • | The multi function display (MFD) in the instrument cluster will display a message at key-on and key-off. |
Conditions for Clearing the DTC
| • | The PCM 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. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
| • | Check the generator voltage sense circuit for high resistance or loose connections. These could cause an intermittent overcharging condition. Refer to Charging System Test . |
| • | Using the Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Failure Records data can aid in determining the distance travelled since the DTC reported a pass and/or fail. Operate the vehicle within the same Failure Records conditions (RPM, load, vehicle speed, temperature, etc.) that you observed. This will isolate when the DTC failed. |
| • | For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Body and Accessories-Wiring Systems. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics in Engine Controls - 5.7L Connector End View Reference: Engine Controls Connector End Views in Engine Controls - 5.7L | ||||
1 | Did you perform the Engine Electrical Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the Ignition 1 Signal parameter is less than the specified value? | 18.0 V | Go to Step 4 | Go to Step 3 |
3 | Measure the voltage at the battery and compare it with the Ignition 1 Signal parameter in the PCM data list. Are the battery voltage and PCM Ignition 1 readings different by more than the value specified? | 0.5 V | Go to Step 4 | Go to Charging System Test |
4 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 5.7L. Did you complete the replacement? | -- | Go to Step 5 | -- |
5 |
Does the scan tool indicate that DTC P0563 failed this ignition? | -- | Go to Step 3 | System OK |
