P1A93

DTC P1A93 or P1A94

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 Descriptors
DTC P1A93
- 14 Volt Power Module Stuck Off

DTC P1A94
- 14 Volt Power Module Stuck On




Circuit/System Description

The starter/generator control module (SGCM) monitors auxiliary power module (APM) On/Off, DC - DC direction is commanded On but converter is Off to check the status of the 14 volt power module. The SGCM also monitors to detect the APM on when it is not commanded On causing a large current output. If a fault is detected, the appropriate DTC will set.


Conditions for Running the DTC

P1A93, P1A94

The engine is running.


Conditions for Setting the DTC

P1A93

In normal charge mode, 12-volt output voltage - 12-volt command voltage is greater than 0.2 volt for 1 second.

P1A94

DC-DC direction is Off, but converter remains On and APM current is greater than +/-20 amps for 1 second.


Action Taken When the DTC Sets


P1A93, P1A94
* Stop PWM (MGU shutdown)
* APM PWM off
* Battery disconnection (disconnect SW on/off)



Conditions for Clearing the DTC

P1A93, P1A94

Clears 30 seconds after cycle wakeup signal.


Diagnostic Aids


P1A93
* Electrical failure in SGCM, open circuit or open fuse
* FET breakdown


P1A94

FET breakdown


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 Testing

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.


Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.


1. Gain access to the 12 volt 175 amp SGCM maxi fuse. Refer to Generator Control Module Cover Replacement ().
2. Test for B+ at 175 amp maxi fuse.

• If less than specified value, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit 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