Lexus ES: Diameter of the Tire is not Uniform (C1337)

DESCRIPTION

The 4WD ECU assembly outputs this DTC if a difference in tire size is detected.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1337	Diameter of the Tire is not Uniform	When the following continues for 36 seconds or more: At a vehicle speed of 30 km/h (19 mph) or more, the average speed difference between the front wheel and rear wheel is 4% or more.	Tire size or pressure (front and rear tires) Speed sensor circuit Front speed sensor Rear skid control sensor Front speed sensor rotor (front axle hub sub-assembly) Rear speed sensor rotor (rear axle hub and bearing assembly) Wire harness or connector Skid control ECU (brake actuator assembly) 4WD ECU assembly

WIRING DIAGRAM

Refer to DTC C1296.

Click here

PROCEDURE

1.	CHECK TIRE CONDITION

(a) Check the size and condition of all 4 tires.

HINT:

This DTC is output when tire deformation or a difference in tire size is detected.

OK:

The diameter and air pressure of all 4 tires are the same.

NG

PERFORM AIR PRESSURE ADJUSTMENT OR REPLACE TIRES SO THAT ALL 4 TIRES ARE SAME IN SIZE

OK

2.	CHECK FOR DTC

(a) Clear the DTCs.

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 30 km/h (19 mph) or more for 36 seconds or more and check if the same DTC is output.

Chassis > Four Wheel Drive > Trouble Codes

(d) Check if any speed sensor DTCs (electronically controlled brake system DTC) are output.

Chassis > Brake/EPB > Trouble Codes

(e) Read the DTCs using the Techstream.

Result	Proceed to
Only DTC C1377 is output	A
No DTCs are not output	B
Speed sensor DTC (electronically controlled brake system DTC) is output	C

B

CHECK FOR INTERMITTENT PROBLEMS

C

REPAIR CIRCUIT INDICATED BY OUTPUT CODE (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)

A

3.	CHECK HARNESS AND CONNECTOR (SPEED SENSOR - SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY))

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

(b) Turn the engine switch off.

(c) Disconnect the A40 skid control ECU (brake actuator assembly) connector.

(d) Disconnect the A46 front speed sensor RH connector, A48 front speed sensor LH connector, b2 rear skid control sensor RH connector and/or b4 rear skid control sensor LH connector .

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

Standard Resistance:

for Front Speed Sensor RH:

Tester Connection	Condition	Specified Condition
A40-21 (FR+) - A46-1 (FR+)	Always	Below 1 Ω
A40-21 (FR+) or A46-1 (FR+) - Body ground	Always	10 kΩ or higher
A40-26 (FR-) - A46-2 (FR-)	Always	Below 1 Ω
A40-26 (FR-) or A46-2 (FR-) - Body ground	Always	10 kΩ or higher

for Front Speed Sensor LH:

Tester Connection	Condition	Specified Condition
A40-24 (FL+) - A48-1 (FL+)	Always	Below 1 Ω
A40-24 (FL+) or A48-1 (FL+) - Body ground	Always	10 kΩ or higher
A40-7 (FL-) - A48-2 (FL-)	Always	Below 1 Ω
A40-7 (FL-) or A48-2 (FL-) - Body ground	Always	10 kΩ or higher

for Rear Skid Control Sensor RH:

Tester Connection	Condition	Specified Condition
A40-22 (RR+) - b2-2 (RA+)	Always	Below 1 Ω
A40-22 (RR+) or b2-2 (RA+) - Body ground	Always	10 kΩ or higher
A40-37 (RR-) - b2-1 (RA-)	Always	Below 1 Ω
A40-37 (RR-) or b2-1 (RA-) - Body ground	Always	10 kΩ or higher

for Rear Skid Control Sensor LH:

Tester Connection	Condition	Specified Condition
A40-39 (RL+) - b4-2 (LA+)	Always	Below 1 Ω
A40-39 (RL+) or b4-2 (LA+) - Body ground	Always	10 kΩ or higher
A40-23 (RL-) - b4-1 (LA-)	Always	Below 1 Ω
A40-23 (RL-) or b4-1 (LA-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.	PERFORM TEST MODE (SIGNAL CHECK)

(a) Turn the engine switch off.

(b) Perform the sensor check in the Test Mode procedure.

Click here

OK:

All Test Mode DTCs are cleared.

NG

GO TO STEP 6

OK

5.	RECONFIRM DTC

(a) Clear the DTCs.

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 30 km/h (19 mph) or more for 36 seconds or more and check if the same DTC is output.

Chassis > Four Wheel Drive > Trouble Codes

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

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

CHECK FOR INTERMITTENT PROBLEMS

6.	CHECK SPEED SENSOR ROTOR

(a) Turn the engine switch off.

(b) Remove the front speed sensor rotor (front axle hub sub-assembly) or rear speed sensor rotor (rear axle hub and bearing assembly).

for Front Side: Click here

for Rear Side: Click here

(c) Check the speed sensor rotor.

OK:

No scratches, oil, or foreign matter on the rotors.

NOTICE:

Check the speed sensor signal after cleaning or replacement.

Click here

NG

CLEAN OR REPLACE SPEED SENSOR ROTOR

OK

7.	REPLACE SPEED SENSOR

(a) Turn the engine switch off.

(b) Replace the front speed sensor or rear skid control sensor.

for Front Side: Click here

for Rear Side: Click here

NOTICE:

Check the speed sensor signal after replacement.

Click here

NEXT

8.	RECONFIRM DTC

(a) Clear the DTC.

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 30 km/h (19 mph) or more for 36 seconds or more so that the same DTC is output.

Chassis > Four Wheel Drive > Trouble Codes

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

HINT:

Reinstall the sensor, connectors, etc. and restore the vehicle to its prior condition before rechecking DTCs.

B

END

A

9.	REPLACE BRAKE ACTUATOR ASSEMBLY

(a) Replace the brake actuator assembly.

Click here

NEXT

10.	RECONFIRM DTC

(a) Clear the DTC.

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 30 km/h (19 mph) or more for 36 seconds or more so that the same DTC is output.

Chassis > Four Wheel Drive > Trouble Codes

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

A

REPLACE 4WD ECU ASSEMBLY

B

END

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