P0AF7
DTC P0AF7
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0AF7
- 14 Volt Power Module Overtemperature
Circuit/System Description
The auxiliary power module (APM) temperature sensor is used for overheat protection. The thermistor is located on the control board, near the phase APM power MOSFET. The starter/generator control module (SGCM) monitors the board temperature sensor for an APM overtemperature condition.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
APM temperature sensor is greater than 80°C (175°F) for 2 seconds.
Action Taken When the DTC Sets
APM PWM off
Conditions for Clearing the DTC
FET temperature for APM is less than 150°C (302°F) for 2.5 seconds.
Diagnostic Aids
Possible engine or SGCM cooling system failure due to the following:
* Restricted radiator air flow
* Restricted engine coolant flow
* Faulty thermostat
* Faulty engine water pump
* Inoperative SGCM water pump
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 all 12-volt battery connections for a short to ground as follows:
* At battery
* At SGCM
* At fuse block
2. If all connections are normal, replace the SGCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests