P1A56

DTC P1A56

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC P1A56
- Hybrid System Voltage Discharge Circuit




Circuit/System Description

The starter/generator control module (SGCM) monitors connector X2 terminals 15 and 16. When the connector is disconnected, the SGCM capacitors are electrically connected to a discharge resistor.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

36-volt output voltage greater than 10 volts and discharge resistance error signal is ON for 1 second.


Action Taken When the DTC Sets

Hybrid system is disabled.


Conditions for Clearing the DTC

Clears 30 seconds after cycle wakeup signal.


Diagnostic Aids

Possible cable open or SGCM internal problem.


Reference Information
Schematic Reference

Hybrid Controls Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool Information


Circuit/System Verification

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.


Check the harness connector X2 for an open/high resistance.

If the connection tests normal, replace the SGCM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning)for SGCM replacement, setup, and programming