P1A93

DTC P1A93 or P1A94

DTC Descriptor

DTC P1A93
- 14 Volt Power Module Stuck Off

DTC P1A94
- 14 Volt Power Module Stuck On

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

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.

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.

1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics
2. If DTC is current, replace the SGCM.

Repair Instructions

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

Control Module References for SGCM replacement, setup, and programming.