P1A89

DTC P1A89

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC P1A89
- 42 Volt System Voltage Low

Circuit/System Description

The accessory DC power control module supplies the energy that flows between the high voltage, 300 volt, DC and intermediate voltage, 42 volt, DC to support the electric power steering. The accessory DC power control module receives a 42 volt enable command from the hybrid powertrain control module over serial data. 42 volt accessory DC power module functions will run only when the 42 volt accessory DC power control module enable is active through serial data.

Conditions for Running the DTC

Accessory DC power control module 42 volt output commanded on.

Conditions for Setting the DTC

42 volt circuit below 21 volts during operation.

Action Taken When the DTC Sets

* DTC P1A89 is a Type C DTC.
* The accessory DC power control module will shutdown 42 volt conversions.

Conditions for Clearing the DTC

DTC P1A89 is a Type C DTC.

Diagnostic Aids

The 42 volt circuit is only used by the electronic power steering. The accessory DC power control module can apply 42 volts on the connector without being connected to the electronic power steering.

Reference Information
Schematic Reference

Hybrid Controls Schematics Hybrid Controls Schematics
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

Drive Motor Generator Control Module Description and Operation Drive Motor Generator Control Module Description and Operation
Electrical Information Reference

* Circuit Testing Circuit Testing
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Engine running, verify the scan tool 42V Circuit Voltage parameter on the accessory DC power control module data list is greater than 40V.

• If less than the specified value refer to Circuit/System Testing.

2. Verify the scan tool 42V Circuit Voltage parameter is greater than 40V, while rotating the steering wheel back and forth while the vehicle is stationary.

• If less than the specified value, replace the M38 power steering assist motor.

Circuit/System Testing

1. Ignition OFF, disconnect the X2 harness connector at the K1 accessory DC power control module.
2. Ignition ON, command the accessory DC power control module Intermediate Voltage Control on the scan tool to turn On the 42 volt circuit.
3. Test for 40-44 V between the 42 V reference output terminals 1 and 2 at the K1 accessory DC power control module.

• If less than the specified range, replace the K1 accessory DC power control module.

4. If the accessory DC power control module 42 V output tests normal, replace the K43 power steering control module.

Repair Instructions

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

* Power Steering Assist Motor Replacement Service and Repair
* Control Module References Control Module References for Accessory DC Power Control Module and the Power Steering Control Module replacement, programming, and setup.