Circuit Description
The PCM continuously monitors the system voltage. The system voltage information is taken from the PCM's ignition feed circuit. When the PCM detects a high or low voltage condition, the PCM operates in a default mode. If the system voltage is low, the PCM raises the idle speed in order to increase the generator output. If the system voltage is high, the PCM disables most outputs in order to protect the hardware . The Class 2 Serial Data circuit is shut down when system voltage is below 9.2 volts or above 16 volts. A scan tool may not display data if system voltage is outside of this range. Because of this, monitor the system voltage when diagnosing a current condition using a DMM J 39200 .
Conditions for Running the DTC
| • | The engine operates longer than 10 seconds. |
| • | The engine speed is greater than 1000 RPM. |
| • | The vehicle speed is greater than 8 km/h (5 mph). |
Conditions for Setting the DTC
The PCM senses system voltage above 18.0 volts for 5 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 during which the diagnostic fails. The PCM stores this information in the Failure Records. |
| • | The PCM disables most outputs. |
| • | The transmission defaults to third gear. |
| • | The TCC operation is inhibited. |
| • | During the time the fault is present, the PCM will cycle the fans ON and OFF every few seconds. |
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\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are installed
correctly. The gaskets prevent contaminate intrusion into the PCM\TAC
modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/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. |
| - | Mis-routed harness. |
| - | Rubbed through wire insulation. |
| - | Broken wire inside the insulation. |
| • | Test the generator voltage sense circuit for high resistance or loose connections. These could cause an intermittent overcharging condition. Refer to Charging System Check in Engine Electrical. |
| • | Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | 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? | 18V | Go to Diagnostic Aids | ||
3 | Repair the Charging system. Refer to Charging System Check in Engine Electrical. 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 |
