Toyota CH-R 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 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.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C146C	Open in ABS Motor Relay Circuit	Any of the following is detected: When the ABS motor relay is actuated, voltage is not supplied to the pump motor. When the ABS motor relay is not actuated, voltage in the pump motor is high. The skid control ECU judges that pump motor operation is abnormal.	ABS MTR NO. 1 fuse ABS motor relay circuit ABS motor relay (brake actuator assembly)

DTC Detection Conditions: C146C

		Vehicle Condition
		Pattern 1	Pattern 2	Pattern 3
Diagnosis Condition	-	-	-	-
Malfunction Status	When the ABS motor relay is actuated, voltage is not supplied to the pump motor.	○	-	-
	When the ABS motor relay is not actuated, voltage in the pump motor is high.	-	○	-
	The skid control ECU judges that pump motor operation is abnormal.	-	-	○
Detection Time		-	-	-
Number of Trips		1 trip	1 trip	1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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

1.	PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Select the Active Test using the Techstream.

Click here

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

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

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

Tester Display
Motor Relay

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

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

B

GO TO STEP 3

A

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, motor relay inspection and 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) Turn the ignition switch off.

(b) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC/EPB > Clear DTCs

(c) Turn the ignition switch off.

(d) Start the engine.

(e) Drive the vehicle at a speed of 40 km/h (25 mph) or more for 30 seconds or more.

(f) Check if the same DTC is output.

Click here

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

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

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

3.	CHECK HARNESS AND CONNECTOR (+BM TERMINAL)

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

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

(b) Disconnect the A42 skid control ECU (brake actuator assembly) connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A42-1 (+BM) - Body ground	Always	11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BM CIRCUIT)

OK

4.	CHECK HARNESS AND CONNECTOR (GND2 TERMINAL)

(a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition A42-14 (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)