Toyota Tundra Service Manual: Communication Error from ECM to VSC (P1631)

Toyota Tundra Service Manual / Engine, Hybrid System / Cruise Control / Dynamic Radar Cruise Control System / Communication Error from ECM to VSC (P1631)

DESCRIPTION

The ECM sends signals such as A/T information signals, dynamic radar cruise control operation signals, brake operation demand signals, and buzzer operation demand signals to the skid control ECU (brake actuator assembly) when the dynamic radar cruise control is operating. Therefore, if the skid control ECU (brake actuator assembly) detects a communication error with the ECM, it sends a malfunction signal back to the ECM.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P1631

Communication Error from ECM to VSC

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 logical error signal from the skid control ECU (brake actuator assembly) for approximately 1 second or more.
  • CAN communication circuit
  • ECM
  • Skid control ECU (brake actuator assembly)

CAUTION / NOTICE / HINT

NOTICE:

  • Before replacing the ECM, refer to Registration.

    Click here

  • First check the CAN communication system by following How to Proceed with Troubleshooting. After checking that there are no malfunctions in the CAN communication system, proceed with troubleshooting.

    Click here

PROCEDURE

1.

CHECK CAN COMMUNICATION SYSTEM

(a) Using the Techstream, check if the CAN communication system is functioning normally.

Click here

Result

Proceed to

CAN communication system DTCs are not output

OK

CAN communication system DTCs are output

NG
NG

GO TO CAN COMMUNICATION SYSTEM

OK

2.

CHECK FOR DTCs (RADAR CRUISE1)

(a) Clear the DTCs.

Click here

(b) Perform the following to make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the malfunction cannot be detected.

  1. Turn the ignition switch to ON.
  2. Turn the dynamic radar cruise control system on using the cruise control main switch (ON-OFF button).
  3. Drive the vehicle at 36 km/h (22 mph) or more for 1 second or more.

(c) Check for DTCs.

Click here

Result

Proceed to

DTC P1631 is not output

A

DTC P1631 is output

B
A

USE SIMULATION METHOD TO CHECK

B

3.

REPLACE ECM

(a) Replace the ECM.

for 1UR-FE: Click here

for 3UR-FE: Click here

for 3UR-FBE: Click here

NEXT

4.

CHECK FOR DTCs (RADAR CRUISE1)

(a) Clear the DTCs.

Click here

(b) Perform the following to make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the malfunction cannot be detected.

  1. Turn the ignition switch to ON.
  2. Turn the dynamic radar cruise control system on using the cruise control main switch (ON-OFF button).
  3. Drive the vehicle at 36 km/h (22 mph) or more for 1 second or more.

(c) Check for DTCs.

Click here

Result

Proceed to

DTC P1631 is not output

A

DTC P1631 is output

B
A

END
B

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

    Communication Error from VSC to ECM (P1630)

    Parts Location

    See More:

    Toyota Tundra Service Manual > Theft Deterrent System: Data List / Active Test
    DATA LIST / ACTIVE TEST 1. DATA LIST HINT: Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2026 Copyright www.ttundra.com
    0.0353