Kia Forte: Suspension System / Tire Pressure Monitoring System

Kia Forte 2019-2024 (BD) Service Manual / Suspension System / Tire Pressure Monitoring System

Components and components location

Components

1. ESC control module
2. Cluster
3. TPMS SET Switch

4. Wheel speed sensor
5. Tone wheel

Description and operation

Description

Indirect Tire Pressure Monitoring System (TPMS)

Using a wheel speed signal from the ESC, the system analyzes the turning radius of the tire and change in tire stiffness to detect a pressure loss.

TPMS determines under-inflation by calculating pressure loss based on the specified pressure. The recommened pressure must therefore be re-saved by operating the SET button once tires are replaced or pressures are adjusted.

Differences between direct and indirect TPMS

Indirect TPMS

Direct TPMS

•	The turning radius of the tire and change in tire stiffness are calculated indirectly.

•	No air pressure sensor needs to be installed in the unit.

•	The recommended tire pressure has to be re-saved after replacing a tire or adjusting air pressure (by pressing the "SET" button).

•	The infaltion pressure inside the tire is measured using a sensor and then wirelessly transmitted to the unit.

•	A separate unit and four air pressure sensors are required to be installed.

•	Poor performance may occur due to frequency noises as the direct TPMS adopts a wireless transmission method.

Low tire pressure warning lamp

Turn-on condition

•	• When tire pressure is below the allowed threshold

Turn-off condition

•	When the low tire pressure warning light illuminates due to the rapid leak, the warning light will extinguish if tire is inflated above the warnning threshold.

Interferences to normal function of indirect TPMS

Type		Conditions	Symptoms	Possible cause
Driving conditions	Low speed driving	Driving continuously at less than 25kph	No warning issued	Lower reliability of the wheel speed sensor data
	High speed driving	Driving continuously at more than 120kph	Lower performance	Tire characteristics
	Deceleration/Acceleration	Rapid acceleration/ brake	Delay of warning	Lack of effective information
Road condition		Sharp curve or crooked road	Delay of warning	Lack of effective information
Road surface condition		Unpaved or slippery road surfaces	Delay of warning	Lack of effective information
Snow chain		Snow chains are mounted on the vehicle's tires	No warning issued	Lower reliability of the wheel speed sensor data

Troubleshooting

Symptom

Possible cause

Remedy

Low tire pressure warning lamp turns on at the correct tire pressure/ Low tire pressure warning lamp fails to turn on at the low pressure

•	SET button has not been pressed after tire replacement or air pressure adjustment.

1.	Check the air pressure.

Check that the wheel inch variant coding procedure has been correctly performed.

–	If the coding is inconsistent with vehicle's options e.g.wheel size,etc. repeat the procedure.

Check the recommended tire pressure level and then press the SET button.

–	Do not press the SET button without verifying the air pressure.

–	Warning light may not be illuminated when driving with snowchains installed, or driving on unpaved roads.

•	SET button has been pressed at the incorrect pressure.

–	SET button has been pressed at the low pressure without filling the tire(s) to specified pressures (regardless of the warning light illumination).

–	SET button has been pressed with tires over or under inflated.

–	SET button has been pressed with significant differences in pressure between tires.

•	When driving with snowchains installed

•	When driving mainly on unpaved/ curved roads

Schematic diagrams

Circuit Diagram

Repair procedures

Adjustment

Indirect TPMS Reset Procedure

1.	Adjust pressure in all 4 tires to the recommended air pressure.

2.	Press the SET button (A) for more than 3 seconds to store the pressure.

3.	Check if system warning light blinks for 4 seconds. (turn off after blinking)

Perform the learning procedure through driving.

•	Perform the learning procedure on a level surface.

•	At least 20 minutes of learning time is required.

Diagnosis procedure using a diagnostic device

Perform the indirect TPMS variant coding using a diagnostic device in case of ESC module replacement.

Removal and Installation

1.	Disconnect the negative battery terminal.

2.	Remove the crash pad lower panel. (Refer to Body - "Crash Pad Lower Panel")

3.	Remove the side crash pad switch panel (A) after loosening the mounting screws.

4.	Disconnect the side crash pad switch connector (A).

5.	Remove the side crash pad switch assembly (A) from the side crash pad switch panel.

6.	Install in the reverse order of removal.

Inspection

1.	Disconnect the TPMS set switch connector from the side crash pad switch.

2.	Operate the TPMS set switch, then check for continuity between terminals and TPMS set switch connector.

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