Toyota Tacoma 2015-2018 Service Manual: Open or Short in Front Speed Sensor RH Circuit (C1405,C1406)

DESCRIPTION

Refer to DTCs C1401 and C1402 (See page ).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1405	Open or Short in Front Speed Sensor RH Circuit	Either of the following is detected: An open in the speed sensor signal circuit continues for 0.5 seconds or more. With the +BS terminal voltage at 9.5 V or higher, the sensor power supply voltage decreases for 0.5 seconds or more.	Front speed sensor RH Skid control ECU (Brake actuator assembly) Wire harness or connector
C1406	Open or Short in Front Speed Sensor LH Circuit	Either of the following is detected: An open in the speed sensor signal circuit continues for 0.5 seconds or more. With the +BS terminal voltage at 9.5 V or higher, the sensor power supply voltage decreases for 0.5 seconds or more.	Front speed sensor LH Skid control ECU (Brake actuator assembly) Wire harness or connector

HINT:

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

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information (See page ).

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

(a) Using the Techstream, check for any momentary interruption in the wire harness and connector corresponding to the DTC (See page ).

ABS/VSC/TRAC

Tester Display	Measurement Item	Normal Condition	Diagnostic Note
FR Speed Open	Front speed sensor RH open circuit detection/ Error or Normal	Normal	Error: Momentary interruption
FL Speed Open	Front speed sensor LH open circuit detection/ Error or Normal	Normal	Error: Momentary interruption

OK:

Normal (There are no momentary interruptions.)

HINT:

Perform the above inspection before removing the sensor and connector.

NG

GO TO STEP 4

OK

2.	READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Start the engine.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

(f) According to the display on the Techstream, read the Data List.

ABS/VSC/TRAC

Tester Display	Measurement Item	Normal Condition	Diagnostic Note
FR Wheel Speed	Front wheel speed sensor RH reading/ Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations
FL Wheel Speed	Front wheel speed sensor LH reading/ Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations

(g) Check that there is no difference between the speed value output from the speed sensor displayed on the Techstream and the speed value displayed on the speedometer when driving the vehicle.

HINT:

Factors that affect the indicated vehicle speed include tire size, tire inflation and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, see the reference chart (See page ).

OK:

The speed value output from the speed sensor displayed on the Techstream is the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

HINT:

If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (See page ).

NG

GO TO STEP 4

OK

3.	RECONFIRM DTC

(a) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

(c) Start the engine.

(d) Perform a road test.

(e) Check if the same DTC is recorded (See page ).

Result

Result	Proceed to
DTCs C1405 and C1406 are not output	A
DTCs C1405 and/or C1406 are output	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

4.	INSPECT SKID CONTROL SENSOR WIRE

(a) Remove the skid control sensor wire.

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

Text in Illustration

*1	Skid Control Sensor Wire	-	-
*a	for RH	*b	for LH

Standard Resistance:

for RH

Tester Connection	Condition	Specified Condition
Va1-1 - S4-1 (FR-)	Always	Below 1 Ω
Va1-2 - S4-2 (FR+)	Always	Below 1 Ω
Va1-1 - Va1-2	Always	10 kΩ or higher

for LH

Tester Connection	Condition	Specified Condition
Wa1-1 - S3-1 (FL-)	Always	Below 1 Ω
Wa1-2 - S3-2 (FL+)	Always	Below 1 Ω
Wa1-1 - Wa1-2	Always	10 kΩ or higher

NG

REPLACE SKID CONTROL SENSOR WIRE

OK

5.	CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - FRONT SPEED SENSOR)

(a) Turn the ignition switch off.

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

(c) Disconnect the S1 skid control ECU (brake actuator assembly) connector and the S4 and/or S3 front speed sensor connector.

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

Standard Resistance:

for RH

Tester Connection	Condition	Specified Condition
S1-31 (FR+) - S4-2 (FR+)	Always	Below 1 Ω
S1-30 (FR-) - S4-1 (FR-)	Always	Below 1 Ω
S1-31 (FR+) or S4-2 (FR+) - Body ground	Always	10 kΩ or higher
S1-30 (FR-) or S4-1 (FR-) - Body ground	Always	10 kΩ or higher

for LH

Tester Connection	Condition	Specified Condition
S1-18 (FL+) - S3-2 (FL+)	Always	Below 1 Ω
S1-17 (FL-) - S3-1 (FL-)	Always	Below 1 Ω
S1-18 (FL+) or S3-2 (FL+) - Body ground	Always	10 kΩ or higher
S1-17 (FL-) or S3-1 (FL-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.	INSPECT BRAKE ACTUATOR ASSEMBLY (SENSOR OUTPUT)

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Turn the ignition switch to ON.

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

Standard Voltage:

for RH

Tester Connection	Switch Condition	Specified Condition
S4-2 (FR+) - Body ground	Ignition switch ON	8 to 14 V

for LH

Tester Connection	Switch Condition	Specified Condition
S3-2 (FL+) - Body ground	Ignition switch ON	8 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Front Speed Sensor)
*b	for RH
*c	for LH

OK

REPLACE FRONT SPEED SENSOR

NG

REPLACE BRAKE ACTUATOR ASSEMBLY