Pinpoint Test As: PSCM (Power Steering Control Module) DTC (Diagnostic Trouble Code) U0401:00

Refer to POWER STEERING CONTROLS for schematic and connector information.

Normal Operation and Fault Conditions

Description

Description
The PSCM monitors the HS-CAN messages when the voltage to the PSCM is greater than 10 volts and there are no Diagnostic Trouble Codes (DTCs) present inhibiting PSCM operation.

Pinpoint Test Applicability

Pinpoint Test Applicability
This test applies to PSCMDTC U0401 Invalid Data Received from the PCM only. It does not apply to any other module except the PSCM.

DTC Diagnostic Strategy

DTC Diagnostic Strategy
If the module DTC list results in a large number of Diagnostic Trouble Codes (DTCs), diagnose all module hard faults first (C102D, C1B00, C200B, C200C, C200D, U2011 and U3000) before diagnosing any network faults (lost communication or invalid data). If voltage concern Diagnostic Trouble Codes (DTCs) are present, diagnose those after any module hard faults and before any network faults. Diagnose all current and active Diagnostic Trouble Codes (DTCs) before diagnosing any historic Diagnostic Trouble Codes (DTCs).

Pinpoint Test Purpose

Pinpoint Test Purpose
To direct the diagnosis to the module and associated circuit sending the faulty or unknown information in the messages.

Diagnostic Aids

Diagnostic Aids
For additional information on the messages sent to the PSCM from the PCM module, refer to Network Message Chart of the service information.
DTC U0401:00 indicates a concern with the PCM. The module reporting this DTC is not the problem module. Do not install a new PSCM as part of the repair for PSCMDTC U0401:00.
When this DTC is set, steering assist is reduced resulting in higher steering efforts during low speed maneuvers.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PSCM U0401:00	Invalid Data Received from ECM/PCM A: No Sub Type Information	This DTC is set if the PSCM receives an "fault" or "unknown" message from the PCM instead of valid sensor information.

Possible Sources

Visual Inspection and Pre-checks

This DTC sets when the PSCM does not receive the PCM messages within a certain time frame. This can occur if the PCM wiring harness or electrical connectors are loose or damaged, or if the vehicle battery state of charge levels are low. Consult the DTC Index for additional information if needed.
Refer to Steering GSB for additional connector and wiring inspection tips. Pinpoint Tests AR: PSCM DTC U023A Lost Communication With The Image Processing Module "A"