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

Toyota Tacoma (2015-2018) Service Manual / Cruise Control / Dynamic Radar Cruise Control System(for 2gr-fks) / Lost Communication with ECM / PCM "A" (U0100,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	MIL
U0100	Lost Communication with ECM / PCM "A"	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	Does not come on
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	Does not come on
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 angle sensor and the millimeter wave radar sensor assembly is detected for approximately 1 second or more.	CAN communication system Steering angle sensor Millimeter wave radar sensor assembly	Does not come on
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 (master cylinder solenoid)1 or skid control ECU (brake actuator assembly)2 and the millimeter wave radar sensor assembly is detected for approximately 2.5 seconds or more.	CAN communication system Skid control ECU (master cylinder solenoid)1 Skid control ECU (brake actuator assembly)2 Millimeter wave radar sensor assembly	Does not come on

*1: for Hydraulic Brake Booster
*2: for Vacuum Brake Booster

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, U0125, U0126 and U0129 are not output	A
DTC U0100, U0125, U0126 or U0129 is output	B

USE SIMULATION METHOD TO CHECK

GO TO CAN COMMUNICATION SYSTEM

Communication Error from ECM to VSC Invalid Serial Data Received (P163181)

DESCRIPTION The ECM sends signals such as dynamic radar cruise control operation signals, brake operation demand signals and buzzer operation demand signals to the skid control ECU (master cylind ...

Lost Communication With ECM/PCM "A" Missing Message (U010087,U010487,U012287)

DESCRIPTION The ECM communicates 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 ...

Other materials:

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Communication Error from VSC to ECM (P1630)
DESCRIPTION The skid control ECU (brake actuator assembly) sends signals such as cruise control cancel signals and brake demand response signals to the ECM when the dynamic radar cruise control system is operating. DTC No. Detection Item DTC Detection Condition ...

Downhill Assist Control Switch Malfunction (Test Mode DTC) (C1379)
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