Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P1A8D: 14 Volt Power Module Voltage Sensor Circuit Low VoltageDTC P1A8E: 14 Volt Power Module Voltage Sensor Circuit High Voltage
Circuit/System Description
The auxiliary power module (APM) 12-volt output voltage is used for a 12-volt line APM output voltage control and a 12-volt line voltage sensor rationality check. The starter/generator control module (SGCM) monitors the voltage sensor for the following:
| • | To detect the failure of the APM 12-volt voltage sensor circuit below valid range. |
| • | To detect the failure of the APM 12-volt voltage sensor circuit above valid range. |
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
P1A8D
Sensor output voltage less than 0.5 volt for 0.5 ms and the 12-volt power supply - 12-volt output voltage is greater than 5 volts for 0.5 ms.
P1A8E
Sensor output voltage greater than 4.2 volts (30.2 volts) for 0.5 ms and the 12-volt power supply - 12-volt output voltage is greater than 5 volts for 0.5 ms.
Action Taken When the DTC Sets
P1A8D, P1A8E
| • | Stop PWM (MGU shutdown). |
| • | APM PWM off. |
Conditions for Clearing the DTC
P1A8D, P1A8E
Clears 30 seconds after cycle wake up signal.
Diagnostic Aids
P1A8D
Possible sensor short to ground or open.
P1A8E
Possible short to voltage or open.
Reference Information
Schematic Reference
Connector End View Reference
Hybrid Controls Connector End Views
Electrical Information Reference
Scan Tool Reference
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.
P1A8D, P1A8E
- If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections .
- If DTC is current, replace the SGCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for SGCM replacement, setup, and programming.
