Toyota Tundra Service Manual: Open in ABS Motor Relay Circuit (C146C)

DESCRIPTION

The ABS motor relay supplies power to the pump motor. While the ABS is activated, the skid control ECU (brake actuator assembly) turns the ABS motor relay on to operate the pump motor.

If the voltage supplied to the ABS motor relay (+BM) is too low due to low voltage from the battery or alternator, this DTC may be stored.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

• When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

  Click here

• Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

When C1241 and/or C1417 is output together with C146C, inspect and repair the trouble areas indicated by C1241 and/or C1417 first.

for C1241: Click here

for C1417: Click here

PROCEDURE

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.

(d) Check the operating sound of the pump motor when operating it using the Techstream.

B

GO TO STEP 3

A

HINT:

This DTC is stored when a problem is identified in the skid control ECU (brake actuator assembly).

The ABS motor relay is in the skid control ECU (brake actuator assembly).

Therefore, ABS motor relay inspection and ABS motor relay unit inspection cannot be performed. Be sure to check if the DTC is output again before replacing the skid control ECU (brake actuator assembly).

(a) Clear the DTCs.

Click here

(b) Turn the ignition switch off.

(c) Start the engine.

(d) Drive the vehicle at a speed of 9 km/h (6 mph) or more for 30 seconds or more.

(e) Check if the same DTC is output.

Click here

HINT:

• If a speed signal of 9 km/h (6 mph) or more is received by the skid control ECU (brake actuator assembly) with the ignition switch ON, the skid control ECU (brake actuator assembly) performs self diagnosis of the motor circuit.
• If the normal system code is output (no DTCs are output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU (brake actuator assembly).
• If any DTCs are output while jiggling a connector or wire harness of the skid control ECU (brake actuator assembly), inspect and repair the connector or wire harness.
• If no DTCs were output when reconfirming DTCs, checking for intermittent problems is necessary because it is suspected that the original DTCs were stored due to the poor connection of a connector terminal.

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

(a) Turn the ignition switch off.

*a Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(c) Disconnect the A57 skid control ECU (brake actuator assembly) connector.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

(e) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BM CIRCUIT)

OK

(a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition A57-13 (GND2) - Body ground Always Below 1 Ω

*a Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND2 CIRCUIT)