Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Cancellation of 4WD Control (C1299)

DESCRIPTION

This DTC is stored if the heat generated by the transmission coupling assembly exceeds a certain amount or the estimated oil temperature of the transfer exceeds a certain amount while driving.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1299	Cancellation of 4WD Control	When one of the following conditions is met: The heat generated by the differential coupling exceeds a certain amount. The estimated oil temperature of the transfer exceeds a certain amount.	Condition, size or tire pressure of the front or rear tires Vehicle stability control system Suspension and ball joint Drive shaft Propeller shaft Transmission coupling assembly 4WD ECU assembly

CAUTION / NOTICE / HINT

NOTICE:

When the 4WD ECU assembly is replaced with a known good one from another vehicle, it is necessary to perform calibration.

Click here

HINT:

Check the condition of each related circuit connector before troubleshooting.

Click here

PROCEDURE

1.	CHECK VEHICLE USAGE

(a) Check that there has been no unintended vehicle usage.

OK:

There is no evidence of rough use (the vehicle has not been driven on damaged or snowy roads, etc. for long periods of time).

NG

CHECK FOR INTERMITTENT PROBLEMS

OK

2.	CHECK FOR DTC

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Check if vehicle stability control system DTCs are output.

Chassis > Brake/EPB > Trouble Codes

(e) Read the DTCs using the Techstream.

Result	Proceed to
Only DTC C1299 is output	A
DTC C1299 and other DTCs (vehicle stability control system DTC)	B

B

REPAIR CIRCUIT INDICATED BY OUTPUT CODE (VEHICLE STABILITY CONTROL SYSTEM)

A

3.	CHECK RELATED PART

(a) Check the condition, size and tire pressure of the front and rear tires.

(b) Inspect the suspension, ball joints, etc. for rattles.

(c) Inspect the drive shaft and propeller shaft rotation condition.

NG

REPAIR OR REPLACE MALFUNCTIONING PARTS

OK

4.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more and check that the same DTC is output.

Click here

Chassis > Four Wheel Drive > Trouble Codes

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

B

CHECK FOR INTERMITTENT PROBLEMS

A

5.	REPLACE 4WD ECU ASSEMBLY

(a) Replace the 4WD ECU assembly.

Click here

NEXT

6.	RECHECK DTC

(a) Clear the DTCs.

Click here

Chassis > Four Wheel Drive > Clear DTCs

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more and check that the same DTC is output.

Click here

Chassis > Four Wheel Drive > Trouble Codes

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

A

REPLACE ELECTRO MAGNETIC CONTROL COUPLING SUB-ASSEMBLY

B

END