Lexus ES: Malfunction in Motor (C1427)

DESCRIPTION

When the power switch is on (READY), the stop light switch assembly off and the vehicle speed is 20 km/h (12 mph) or more, the skid control ECU (brake booster with master cylinder assembly) performs a self-diagnosis of the ABS motor relay circuit during the initial check of the actuator.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C1427	Malfunction in Motor	1159	The pump motor built into the brake actuator assembly is not operating correctly.	Wire harness or connector Pump motor or pump motor circuit built into the brake actuator assembly	Comes on	INF Code 1159: SAE Code C1427 Electronically controlled brake system DTC

MONITOR DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) monitors the voltage of the ABS motor. When the ABS motor is normal and the ABS motor relay is turned off, the voltage of the ABS motor drops gradually due to rotational inertia; however, if the ABS motor is not turning and the ABS motor relay is turned off, the voltage of the ABS motor drops immediately. If the voltage of the ABS motor drops considerably quickly when the ABS motor relay is turned off, the skid control ECU (brake booster with master cylinder assembly) judges that the ABS motor is not operating and illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C1427: ABS pump motor stuck
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	2 times
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
Both of the following conditions are met	-
Skid control ECU (brake booster with master cylinder assembly) state	Initial check
After command to ABS motor relay on to off detection, 0.002 seconds passes	Met

TYPICAL MALFUNCTION THRESHOLDS

ABS pump motor voltage

Less than 1.3 V for 0.022 seconds or more within 0.024 seconds

COMPONENT OPERATING RANGE

All of the following conditions are met	-
Skid control ECU (brake booster with master cylinder assembly) state	Initial check
After command to ABS motor relay on to off detection, 0.002 seconds passes	Met
ABS pump motor voltage	Less than 1.3 V for less than 0.022 seconds within 0.024 seconds

CONFIRMATION DRIVING PATTERN

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

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

(a) Select the Active Test on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > 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 > Active Test

Tester Display
Motor Relay

(b) Check the operating sound of the ABS motor relay when operating it with the Techstream.

Result	Proceed to
The operating sound is heard.	A
The operating sound is not heard.	B

B

GO TO STEP 3

A

2.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

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

(d) Perform a road test.

(e) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C1427 is not output.	A
DTC C1427 is output.	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

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

(a) Turn the power switch off.

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

OK:

The connector is securely connected.

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

(d) Disconnect the A54 brake actuator assembly connector.

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

OK:

No deformation or corrosion.

(f) 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

4.	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

5.	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
DTC C1427 is not output.	A
DTC C1427 is output.	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

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