Lexus ES manuals

Lexus ES: Open Circuit in ABS Motor Relay Circuit (C146C,C146D)

Lexus ES (XZ10) Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System (for Hv Model) / Open Circuit in ABS Motor Relay Circuit (C146C,C146D)

DESCRIPTION

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

During ABS, TRAC, VSC, brake hold, secondary collision brake 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

MIL

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

Comes on
  • INF Code 612: SAE Code C052E
  • 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

Comes on
  • INF Code 613: SAE Code C052D (Case 1)
  • ABS DTC

MONITOR DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) monitors the voltage of the ABS motor.

When the ABS motor relay is instructed to be on and the voltage of the ABS motor is within the range of an open circuit malfunction, or when the ABS motor is instructed to be off and the voltage of the ABS motor is within the range of a short circuit malfunction, an open circuit or short circuit is judged respectively and the MIL is illuminated and a DTC is stored.

MONITOR STRATEGY

Related DTCs

C052D (Case 1): ABS pump motor circuit high

C052E: ABS pump motor open circuit

Required Sensors/Components(Main)

Brake actuator assembly

Required Sensors/Components(Related)

Skid control ECU (brake booster with master cylinder assembly)

Brake actuator assembly

Frequency of Operation

Continuous

Duration

0.2 seconds: C052E

4 seconds: C052D (Case 1)

MIL Operation

Immediately

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

All

Monitor runs whenever the following DTCs are not stored

None
C052E

Either of the following conditions is met

A or B

A. Both of the following conditions are met

-

ABS pump motor voltage is 7.607 V or more experience

Not met

Command to ABS motor relay

On

B. All of the following conditions are met

-

ABS pump motor voltage is 7.607 V or more experience

Met

Command to ABS motor relay

On

Power supply for ABS motor

Higher than 9.13 V
C052D (Case 1)

Command to ABS motor relay

Off

TYPICAL MALFUNCTION THRESHOLDS

C052E

ABS pump motor voltage

Less than 7.607 V
C052D (Case 1)

ABS pump motor voltage

7.607 V or more, and less than 18.57 V

COMPONENT OPERATING RANGE

C052E

Both of the following conditions are met

-

Command to ABS motor relay

On

ABS pump motor voltage

7.607 V or more
C052D (Case 1)

ABS pump motor voltage

Less than 7.607 V, or 18.57 V or more

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the power switch on (IG).
  3. Turn the Techstream on.
  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  5. Turn the power switch off.
  6. Turn the power switch on (IG).
  7. Turn the Techstream on.
  8. Wait 4 seconds.
  9. Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
  10. Read the DTCs.

    HINT:

    • If a DTC is output, the system is malfunctioning.
    • If a DTC is not output, perform the following procedure.
  11. If the DTCs are not output, perform a universal trip and check for permanent DTCs.

    Click here

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTCs are output, the system is normal.

WIRING DIAGRAM

Refer to DTC C1427.

Click here

CAUTION / NOTICE / HINT

NOTICE:

  • 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.

HINT:

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

1.

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.

OK:

The connector is securely connected.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

(b) Disconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector.

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

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A45-41 (BM) - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BM CIRCUIT)
OK

2.

CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY)

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

OK:

The connector is securely connected.

(b) Disconnect the A54 brake actuator assembly connector.

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

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A45-40 (+BM) - A54-10 (+BM)

Always

Below 1 Ω

A45-40 (+BM) or A54-10 (+BM) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (GND TERMINAL)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A54-1 (MGND) - Body ground

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Brake Actuator Assembly)
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
OK

4.

RECONFIRM DTC

(a) Reconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector.

(b) Reconnect the A54 brake actuator assembly connector.

(c) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(d) Turn the power switch off.

(e) Turn the power switch on (READY).

(f) Perform a road test.

(g) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result

Proceed to

DTCs C146C and C146D are not output.

A

DTCs C146C and/or C146D are output.

B

HINT:

  • 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

B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

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