P0A88

DTC P0A88 or P0A89

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 Descriptors
DTC P0A88
- 14 Volt Power Module Current Sensor Circuit Low Current

DTC P0A89
- 14 Volt Power Module Current Sensor Circuit High Current

Circuit/System Description

The auxiliary power module (APM) current sensor is used for over current limitation (less than 150 A). The current sensor is soldered on the control board, near the APM 12-volt bus bar. The starter/generator control module (SGCM) monitors the current sensor for the following:

* To detect the failure of the APM current sensor circuit (high).
* To detect the failure of the APM current sensor circuit (low).

If one of the above conditions is detected, the SGCM will set the appropriate DTC.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

P0A88

Sensor signal for APM is less than 0.5 volt (-376 A) for 0.5 ms.

P0A89

Sensor signal for APM is greater than 4.5 volts (376 A) for 0.5 ms.

Action Taken When the DTC Sets

P0A88, P0A89

APM PWM off.

Conditions for Clearing the DTC

P0A88, P0A89

Clears 30 seconds after cycle wake up signal.

Diagnostic Aids

P0A88

Possible current sensor short to ground or open.

P0A89

Possible current sensor short to voltage.

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.

P0A88, P0A89
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.