DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0129: Lost Communication with Brake System Control Module: Description

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.

The power steering ECU assembly receives signals from the ECM and skid control ECU via CAN communication

DTC DETECTION CONDITION CHART

DTC No.	DTC Detection Item	Inspection Area
U0100	ECM communication error	CAN communication system ECM (when only U0100 is output)
U0129	Skid control ECU communication error	CAN communication system Skid control ECU (when only U0129 is output)

HINT.

When 2 or more DTCs starting with "U" are output simultaneously, inspect the connectors and wire harness of each ECU.
If the power steering ECU assembly detects DTC U0129 only, it adjusts the amount of power assistance for a speed of 100 km/h (62 mph) and continues system control.