C146C, C146D

DTC Code	DTC Name
C146C	Open Circuit in ABS Motor Relay Circuit
C146D	Short Circuit in ABS Motor Relay Circuit

DESCRIPTION

The ABS motor relay is built into the brake booster with master cylinder assembly.

During ABS, TRC, VSC or brake assist operation, the skid control ECU (brake booster with master cylinder assembly) turns on the ABS motor relay to run the pump motor in the brake actuator assembly.

When any DTC related to the ABS motor is stored, the IC built into the skid control ECU (brake booster with master cylinder assembly) operates in fail-safe mode.

When the supplied voltage to the BM terminal of the ABS motor relay is excessively low due to an auxiliary battery or charging circuit malfunction, DTC C146C and/or C146D is stored.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	Note
C146C	Open Circuit in ABS Motor Relay Circuit	612	When operation of the ABS motor is requested, the ABS motor voltage is less than 7.6 V for 0.2 seconds or more.	Wire harness or connector Skid control ECU (brake booster with master cylinder assembly) Brake actuator assembly	ABS DTC
C146D	Short Circuit in ABS Motor Relay Circuit	613	A short in the ABS motor relay drive circuit is detected for 4 seconds or more.	Wire harness or connector Skid control ECU (brake booster with master cylinder assembly) Brake actuator assembly	ABS DTC

WIRING DIAGRAM

Refer to DTC C1427.

Click here

CAUTION / NOTICE / HINT

Note

After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".

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

Tech Tips

When DTCs C1241 and/or C1417 are output together with C146C and/or C146D, inspect and repair the trouble areas indicated by C1241 and/or C1417 first.

for C1241: Click here

for C1417: Click here

PROCEDURE

CHECK HARNESS AND CONNECTOR (BM TERMINAL)

*a
Front view of wire harness connector

(to Skid Control ECU (Brake Booster with Master Cylinder 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 A39 skid control ECU (brake booster with master cylinder assembly) connector.
Check both the connector case and the terminals for deformation and corrosion.

OK

No deformation or corrosion.

OK
The connector is securely connected.

OK
No deformation or corrosion.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A39-41 (BM) - Body ground	Always	11 to 14 V

Result

Proceed to
OK
NG

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BM CIRCUIT)

OK

CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - 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 A40 brake actuator assembly connector (for LHD).
Disconnect the A41 brake actuator assembly connector (for RHD).
Check both the connector case and the terminals for deformation and corrosion.

OK

No deformation or corrosion.

OK
The connector is securely connected.

OK
No deformation or corrosion.

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

Standard Resistance

for LHD
Tester Connection	Condition	Specified Condition
A39-40 (+BM) - A40-13 (+BM)	Always	Below 1 Ω
A39-40 (+BM) or A40-13 (+BM) - Body ground	Always	10 kΩ or higher

for RHD
Tester Connection	Condition	Specified Condition
A39-40 (+BM) - A41-13 (+BM)	Always	Below 1 Ω
A39-40 (+BM) or A41-13 (+BM) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

CHECK HARNESS AND CONNECTOR (GND TERMINAL)

*A

for LHD

*B

for RHD

*a

Front view of wire harness connector

(to Brake Actuator Assembly)

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

Standard Resistance

for LHD
Tester Connection	Condition	Specified Condition
A40-1 (MGND) - Body ground	Always	Below 1 Ω

for RHD
Tester Connection	Condition	Specified Condition
A41-1 (MGND) - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

OK

RECONFIRM DTC

Reconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.
Reconnect the A40 brake actuator assembly connector (for LHD).
Reconnect the A41 brake actuator assembly connector (for RHD).
Clear the DTCs.

Click here

Chassis > ABS/VSC/TRC > Clear DTCs
Turn the power switch off.
Turn the power switch on (READY).
Perform a road test.

Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRC > Trouble Codes

Result

Result	Proceed to
DTCs C146C and C146D are not output.	A
DTCs C146C and/or C146D are output. (for LHD)	B
DTCs C146C and/or C146D are output. (for RHD)	C

Tech Tips

If a speed signal of 20 km/h (12 mph) or more is sent to the skid control ECU (brake booster with master cylinder assembly) with the power switch on (IG) and the stop light switch assembly off, the ECU performs self diagnosis of the motor and solenoid circuits.
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 booster with master cylinder assembly).
If any DTCs are output while jiggling a connector or wire harness from the skid control ECU (brake booster with master cylinder assembly), inspect and repair the connector or wire harness.
The DTCs were probably output due to a bad connection of the connector terminal.

A

USE SIMULATION METHOD TO CHECK Click here

B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

C

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C146C, C146D