DTC C146C: Open Circuit in ABS Motor Relay Circuit [04/2018 - 08/2021]: Procedure

PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY)

Connect the Techstream to the DLC3.
Start the engine.

Enter the following menus: Chassis / ABS/VSC/TRAC/EPB / Active Test.

Chassis > ABS/VSC/TRAC/EPB > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Motor Relay	ABS motor relay	Relay OFF/ON	Operating sound of motor can be heard

Chassis > ABS/VSC/TRAC/EPB > Active Test

Tester Display
Motor Relay

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

Result

Result	Proceed to
Operating sound is heard	A
Operating sound is not heard	B

Result:

See step 3

Result:

See step 2

RECONFIRM DTC

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).

Clear the DTCs.
Chassis > ABS/VSC/TRAC/EPB > Clear DTCs
Turn the engine switch off.
Start the engine.
Drive the vehicle at a speed of 40 km/h (25 mph) or more for 30 seconds or more.

Check if the same DTC is output.

Chassis > ABS/VSC/TRAC/EPB > Trouble Codes

Result

Result	Proceed to
C146C is not output	A
C146C is output	B

HINT:

If a speed signal of 40 km/h (25 mph) or more is received by the skid control ECU (brake actuator assembly) with the engine switch on (IG), 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.

Result:

USE SIMULATION METHOD TO CHECK. Refer to HOW TO PROCEED WITH TROUBLESHOOTING [04/2018 -]

Result:

REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to REMOVAL [04/2018 - 08/2020] , or refer to REMOVAL [08/2020 - 08/2021]

CHECK HARNESS AND CONNECTOR (+BM TERMINAL)

Turn the engine switch off.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

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

The connector is securely connected.
Disconnect the A28 skid control ECU (brake actuator assembly) connector.
Check both the connector case and the terminals for deformation and corrosion.
OK

No deformation or corrosion.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A28-1 (+BM) - Body ground	Always	11 to 14 V

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BM CIRCUIT)

Result:

See step 4

CHECK HARNESS AND CONNECTOR (GND2 TERMINAL)

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A28-14 (GND2) - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

Result:

REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to REMOVAL [04/2018 - 08/2020] , or refer to REMOVAL [08/2020 - 08/2021]

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND2 CIRCUIT)