Circuit Description
The powertrain control module (PCM) continuously monitors the system voltage. The system voltage information is taken from the PCM ignition feed circuits. Since voltages below 8.0 volts or above 18.0 volts, could cause improper system operation and/or component damage, the PCM operates in a default mode if a PCM voltage diagnostic trouble code (DTC) sets. If the system voltage is high, the PCM disables most outputs to protect the hardware. A scan tool may not display data if system voltage is outside this range. Use a DMM to monitor system voltage to verify if the fault is currently present. A high voltage may cause a stalling condition, or other driveability concerns.
Conditions for Running the DTC
The engine run time is more than 10 seconds.
Conditions for Setting the DTC
| • | The PCM senses the system voltage is above 18.0 volts. |
| • | All the conditions are present for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM stores DTC P0563 in the PCM memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM will record the operating conditions at the time the diagnostic fails. The PCM stores this information in Failure Records. |
| • | The PCM disables most outputs. |
| • | The transmission defaults to third gear. |
| • | The torque converter clutch (TCC) operation is inhibited. |
| • | The PCM will cycle the cooling fans ON and OFF every few seconds during the time the condition is present. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing/replacing
the PCM. Ensure that the gaskets are installed correctly. The gaskets
prevent contaminate intrusion into the PCM. • For any test that requires probing the PCM or a component
harness connector, use the J 35616
connector test adapter kit. Using this kit prevents damage
to the harness and component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The following may cause an intermittent: |
| - | Poor connections -- Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | Inspect the generator voltage sense circuit for high resistance or loose connections. These could cause an intermittent overcharging condition. |
| • | For an intermittent condition, refer to Symptoms . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Important: If DTC P1635 and/or P1639 are set, refer to DTC P1635 5 Volt Reference 1 Circuit and/or DTC P1639 5 Volt Reference 2 Circuit for further diagnosis. Is the battery voltage less than the specified value? | 18 V | Go to Diagnostic Aids | ||
3 | Repair the charging system. Is the repair completed? | -- | -- | |
4 |
Does the scan tool indicate that this test ran and passed? | -- | ||
5 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
