Tire pressure monitoring is a software module in the ABS/ESP-module for finding slow losses of air pressure. The rpm signal from the ABS-system's wheel sensors is used to separately monitor the rolling circumference for each wheel. When the rolling circumference for a wheel changes, a control light turns on in the combi instrument.
Tires' rolling circumference may change when:
Air pressure is too low.
Tire has structural damage.
The car is loaded on one side.
Wheels on one axle are loaded more heavily (e.g., when driving with a trailer).
Snow chains are installed.
Mini spare wheel is installed.
One or several tires have been replaced.
The system for tire pressure monitoring has a yellow control light in the combi instrument that indicates as follows:
Flashing light indicates that no "FIRST BASIC SETTING" has been performed.
Constant fixed light in combination with a warning sound indicates pressure loss. Check the tire pressure and perform a "BASIC SETTING".
There are different versions of tire pressure monitoring, current instruction applies for PR-number: 7K1, 7K6, and 7K9.
The car's PR-number can be read on the vehicle data plate, usually located in the spare wheel well or on the first page in the service book.
Test conditions:
Ignition on.
Diagnostics unit shall not be connected.
Procedure:
"FIRST BASIC SETTING"
(with flashing control light):
Check tire pressure and adjust as needed.
At the same time, press the ASR/ESP button and the button for tire pressure monitoring (SET) for at least 2 seconds. An acknowledgement tone is heard after successful calibration.
The function is done.
"BASIC SETTING" (with fixed control light and warning sound):
Check tire pressure and adjust as needed.
Press the button for tire pressure monitoring (SET) for at least 2 seconds. An acknowledgement tone is heard after successful calibration.
The function is done.