Multiple U-Code Diagnostic Information - With One Having Symptom Byte 71 (PIT5569C)

Publication date: 2024-09-06
Reference number: PIT5569C
Supersedes refnos: PIT5569, PIT5569A, PIT5569B

MULTIPLE U-CODE DIAGNOSTIC INFORMATION - WITH ONE HAVING SYMPTOM BYTE 71

TECHNICAL SERVICE BULLETIN

Reference Number(s): PIT5569C, Date of Issue: Sep 6, 2024

SERVICE INFORMATION

Brand:	Model:	Model Year:		VIN:		Engine:	Transmission:
Brand:	Model:	from	to	from	to	Engine:	Transmission:
All	All	2013-2023		All	All	All	All

Involved Region or Country	North America
Condition	The following bulletin is intended to provide direction and examples when diagnosing multiple DTCs, one of which includes U**** Byte 71 DTC. Any control module may set DTC for one of its inputs and that data is shared across the communication buss for other modules to do their respective functions. The receiving module may set a 71 byte type DTC. NOTE: In these cases the DTC list should be examined for what control module or missing data the U codes point to and check for DTC's related to the managing control modules' inputs. Symptom Byte -71 Symptom Byte Description Invalid Data Symptom Byte Definition This sub type is used by the Electronic Control Unit to indicate a signal was received with the corresponding validity bit equal to Invalid or post processing of the signal determines it is invalid. As a general rule, never replace components for "Invalid Data Received" codes within the component. Resolve the System-Wide non-Communication (not U codes) first and reevaluate.
Cause	Below is one example in which an intermittent wheel speed sensor code was setting U codes across busses and the root cause was tracked back to the wheel speed sensor and EBCM messages.

CORRECTION

Problem # 1: The DIC shows Service Stabilitrack" and "Service ABS"

Condition: When the EBCM sets any of the wheel sensor codes C0035-C0050, it yields "Service Transmission", "Steering Assist Reduced" and "AWD off" in addition to "Service Stabilitrak" and "Service ABS" messages. This is in addition to several U codes corresponding to the above messages which may include U0121 U0131 B1011 U0414 C0040 U0422 U0415 U2502 U0401 U0403 U0402.

Cause: The EBCM would set the wheel speed sensor code intermittently, triggering a system malfunction message to be transmitted, resulting in multiple U codes across the chassis expansion and HS CAN buses. The multiple U codes can cause misdiagnosis. An erratic wheel speed signal can cause this failure due to the miscommunication in the system when it intermittently fails. When you review the ABS data you may find an erratic signal from the wheel speed sensor. This can be caused by a faulty front hub wheel bearing.

Correction: Diagnose the Wheel Speed Sensor using SI. In this example it was diagnosed that a faulty front hub wheel bearing was the cause of the erratic wheel speed sensor signal.

SERVICE INFORMATION

Version	4
Modified	05/17/2017 - Created on. 07/16/2019 - Updated to add Model Year. 07/05/2022 - Updated to add 2020 -2022 Model Year. 09/06/2024 - Updated to add 2023 Model Year.