P1A8F

DTC P1A8F

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 P1A8F
- 14 Volt Power Module Current Sensor Overcurrent




Circuit/System Description

The starter/generator control module (SGCM) monitors the 14-volt power module current sensor for an overcurrent condition to protect the MOSFET. In the hardware an overcurrent protection circuit is used to limit the current, and software monitors for an overcurrent reading in the sensor.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

The 12 volt charge is greater than 150 amps or less than -150 amps for 2 seconds


Action Taken When the DTC Sets

* In the software fault:

- Stop PWM (MGU shutdown)
- APM PWM off

* In the hardware fault:

- Stop PWM (MGU shutdown)
- APM PWM off
- Battery disconnection (disconnect SW on/off)



Hybrid system is disabled.


Conditions for Clearing the DTC

* In the software fault, APM current less than +/- 10 amps
* 12VOUT is greater than 7 volts.
* APMTEMP is less than 105°C (221°F) for 160 ms.
* Clears 30 seconds after cycle wake up signal.



Diagnostic Aids

* Battery cable short to ground
* Fuse/relay box electrical failures
* 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 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. Inspect for any open fuses.
2. Inspect all the 12-volt battery connections for short to ground as follows:

* At battery
* At SGCM
* At fuse block

3. If all connections test 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