Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: ABS Pump Motor Control Circuit Open (C052C13,C052C49,C052F14)

DESCRIPTION

The motor relay and motor fail safe relay are built into the brake actuator assembly.

When the skid control ECU (brake actuator assembly) operate ABS, TRAC, VSC, brake hold or brake assist, the motor relay turns ON and drives the motor pump built into the brake actuator assembly.

If any DTCs related to motor supply power are stored, fail-safe is performed and supply of power to the motor relay is cut by the motor fail safe relay.

If the voltage supplied to the motor relay (BM) is below the DTC detection threshold due to low voltage from the battery or alternator, these DTCs may be stored.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C052C13	ABS Pump Motor Control Circuit Open	Either of the following is detected: When the +BS terminal voltage is from 9.5 to 17.4 V with the motor relay ON while control operates, a relay contact OFF condition continues for 0.12 seconds or more. When the +BS terminal voltage is from 9.5 to 17.4 V, a motor relay supervision voltage malfunction continues for 0.12 seconds or more when the motor relay turns ON during control operation.	Wire harness and connector Skid control ECU (brake actuator assembly)
C052C49	ABS Pump Motor Control Internal Electronic Failure	Any of the following is detected: When the +BS terminal voltage is from 9.5 to 17.4 V, overcurrent in the motor relay and motor fail-safe relay continues for 0.05 seconds or more. Motor relay overcurrent continues for 0.05 seconds or more. When the +BS terminal voltage is from 9.5 to 17.4 V, a motor relay gate voltage malfunction continues for 0.12 seconds or more.	Wire harness and connector Skid control ECU (brake actuator assembly)
C052F14	ABS Pump Motor Supply Voltage Circuit Short to Ground or Open	When voltage at +BS terminal is 9.5 V or higher, open in BM terminal continues for 1 second or more.	Wire harness and connector Skid control ECU (brake actuator assembly)

DTC Detection Conditions: C052C13

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	When the +BS terminal voltage is from 9.5 to 17.4 V	○	○
Malfunction Status	Motor relay ON while control operates, relay contact OFF condition continues	○	-
	Motor relay supervision voltage malfunction continues, motor relay turns ON during control operation	-	○
Detection Time		0.12 seconds or more	0.12 seconds or more
Number of Trips		1 trip	1 trip

HINT:

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

DTC Detection Conditions: C052C49

		Vehicle Condition
		Pattern 1	Pattern 2	Pattern 3
Diagnosis Condition	When the +BS terminal voltage is from 9.5 to 17.4 V	○	○	-
Malfunction Status	Overcurrent in motor relay and motor fail-safe relay continues	○	-	-
	Motor relay overcurrent continues	-	○	-
	Motor relay gate voltage malfunction continues	-	-	○
Detection Time		0.05 seconds or more	0.05 seconds or more	0.12 seconds or more
Number of Trips		1 trip	1 trip	1 trip

HINT:

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

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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 connectors. OK: The connector is securely connected.

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

(b) Disconnect the A41 skid control ECU (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 voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
A41-46 (BM) - Body ground	Always	11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.	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
A41-30 (GND2) - Body ground	1 minute or more after disconnecting the cable from the negative (-) battery terminal	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

CLEAR DTC

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Operate the Techstream to clear the codes. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Clear DTCs

(e) Press the DTC clear button.

(f) Turn the engine switch off.

NEXT

4.	RECONFIRM DTC

(a) Start the engine.

(b) Drive the vehicle at a speed of 20 km/h (12 mph).

(c) Read the DTCs following the prompts on the Techstream. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Trouble Codes

(d) Check if the same DTC is output.

Result	Proceed to
DTCs C052C13, C052C49 and C052F14 are not output.	A
DTCs C052C13, C052C49 and/or C052F14 are output.	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY