The transmission control module (TCM) continuously monitors the system voltage on the ignition 1 circuit and battery circuit. Higher than normal voltage may cause the solenoids inside the transmission to operate improperly or damage solid-state components inside the TCM.
When the TCM detects high voltage, DTC P0563 sets. DTC P0563 is a type C DTC.
This diagnostic procedure supports the following DTC:
DTC P0563 System Voltage High
The ignition is ON.
The TCM detects system voltage 18-volts or greater for 10 seconds.
| • | The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). | 
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM records this information as a Failure Record. | 
| • | The TCM stores DTC P0563 in TCM history. | 
| • | A scan tool can clear the DTC. | 
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. | 
| • | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. | 
| • | Observe the driver information center (DIC) messaging that would indicate the electrical system requires service. | 
| • | Use the scan tool in order to inspect all other modules for voltage related DTCs. | 
| • | Running the engine with a battery charger attached may cause DTC P0563 to set. | 
| - | Inspect the charging circuit for high resistance. | 
| - | Inspect the vehicle battery for open or sulfated cells. | 
The numbers below refer to the step numbers on the diagnostic table.
This step tests the charging system voltage with a minimal load.
This step obtains the ignition voltage measurement reported by the TCM.
Step  | Action  | Value  | Yes  | No  | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1  | Did you perform the Diagnostic System Check - Vehicle?  | --  | Go to Step 2  | |||||||||
2  | 
 Important: 
 Did you record a Failure Record for DTC P0562?  | --  | Go to DTC P0562  | Go to Step 3  | ||||||||
3  | 
 Is the charge indicator lamp ON?  | --  | Go to Charging System Test  | Go to Step 4  | ||||||||
 Is the voltage within the specified range?  | 12.5-14.5 V  | Go to Step 5  | Go to Charging System Test  | |||||||||
 Is the difference between the voltage displayed on the scan tool and the voltage measurement in Step 4 greater than the specified value?  | 1.0 V  | Go to Step 7  | Go to Step 6  | |||||||||
6  | Did P0563 set again?  | --  | Go to Step 7  | Go to Testing for Intermittent Conditions and Poor Connections  | ||||||||
7  | Replace the TCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement?  | --  | Go to Step 8  | --  | ||||||||
8  | Perform the following procedure in order to verify the repair: 
 
 
 
 
 Has the test run and passed?  | --  | Go to Step 9  | Go to Step 2  | ||||||||
9  | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed?  | --  | System OK  |