Toyota Tacoma (2015-2018) Service Manual: Lost Communication with ECM / PCM "A" (U0100,U0104,U0122,U0125,U0126,U0129)

Toyota Tacoma (2015-2018) Service Manual / Cruise Control / Dynamic Radar Cruise Control System(for 2tr-fe) / Lost Communication with ECM / PCM "A" (U0100,U0104,U0122,U0125,U0126,U0129)

DESCRIPTION

The millimeter wave radar sensor assembly and ECM communicate with each sensor and ECU via CAN communication.

If any malfunction is detected in a CAN communication circuit, one or more CAN communication system DTCs are stored.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
U0100	Lost Communication with ECM / PCM "A"	Condition 1: While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the ECM and the millimeter wave radar sensor assembly is detected for approximately 1 second or more. Condition 2: While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, the ECM continuously receives a communication cut-off signal from the skid control ECU (brake actuator assembly) for approximately 1 second or more.	Condition 1: CAN communication system ECM Millimeter wave radar sensor assembly Condition 2: CAN communication system ECM Skid control ECU (brake actuator assembly)
U0104	Lost Communication with Cruise Control Module	While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the ECM and the millimeter wave radar sensor assembly is detected for approximately 1 second or more.	CAN communication system ECM Millimeter wave radar sensor assembly
U0122	Lost Communication with Vehicle Dynamics Control Module	When the ignition switch is ON and the dynamic radar cruise control system is operating, a communication error between the skid control ECU (brake actuator assembly) and the ECM is detected for approximately 2.6 seconds or more.	CAN communication system ECM Skid control ECU (brake actuator assembly)
U0125	Lost Communication with Yaw Rate Sensor Module	While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the yaw rate sensor and the millimeter wave radar sensor assembly is detected for approximately 1 second or more.	CAN communication system Yaw rate sensor (airbag sensor assembly) Millimeter wave radar sensor assembly
U0126	Lost Communication with Steering Angle Sensor Module	While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the steering sensor and the millimeter wave radar sensor assembly is detected for approximately 1 second or more.	CAN communication system Steering sensor Millimeter wave radar sensor assembly
U0129	Lost Communication with Brake System Control Module	While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the skid control ECU (brake actuator assembly) and the millimeter wave radar sensor assembly is detected for approximately 2.5 seconds or more.	CAN communication system Skid control ECU (brake actuator assembly) Millimeter wave radar sensor assembly

PROCEDURE

1.	CHECK FOR DTCs (RADAR CRUISE 1 AND RADAR CRUISE 2)

(a) Clear the DTCs.

Click here (b) Make sure that the DTC detection conditions are met.

(b) Make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the system cannot detect the malfunction.

Turn the ignition switch to ON.
Turn the dynamic radar cruise control system on using the cruise control main switch (ON-OFF button).
Drive the vehicle at 36 km/h (22 mph) or more for 5 seconds or more.

Click here

Result	Proceed to
DTC U0100, U0104, U0122, U0125, U0126, U0129 and U0137 are not output	A
DTC U0100, U0104, U0122, U0125, U0126, U0129 or U0137 is output	B

USE SIMULATION METHOD TO CHECK

GO TO CAN COMMUNICATION SYSTEM

Fail-safe Chart

FAIL-SAFE CHART HINT: If any of the following auto cancel conditions are detected while the dynamic radar cruise control system is controlling vehicle speed, the system clears the stored vehicle ...

Vehicle Control History

VEHICLE CONTROL HISTORY VEHICLE CONTROL HISTORY HINT: A part of the control history can be confirmed using the vehicle control history. Click here ...

Other materials:

Check Bus 3 Line for Short to +B
DESCRIPTION There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and t ...

Taillight Relay Circuit
DESCRIPTION The main body ECU (multiplex network body ECU) controls the operation of the TAIL relay. WIRING DIAGRAM CAUTION / NOTICE / HINT NOTICE: Inspect the fuses for circuits related to this system before performing the following inspection procedure. If the main body EC ...

Vehicle Speed Sensor "A" No Signal (P050031)
DESCRIPTION The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. The skid control ECU converts these wheel speed signals into a pulse signal and outputs it to the ECM via the combination meter. The ECM determines the vehicle speed based on the fr ...