Diagnostic Functions

Diagnostic functions

Tire pressure monitoring system (TPMS)
The central electronic module (CEM) can store diagnostic trouble codes (DTCs) if there is a fault in the receiver or a fault in any of the sensors. In order to carry out a correct evaluation of the function, the vehicle must have traveled faster than 40 km/h (25 mph) for longer than 570 seconds (approximately 9.5 minutes). This time is accumulated time, i.e. the time is interrupted if the vehicle drops below 40 km/h (25 mph), if stopping at traffic lights for example. Counting continues as soon as the vehicle exceeds 40 km/h (25 mph) again.
The central electronic module (CEM) can store two diagnostic trouble codes (DTCs) per sensor. A diagnostic trouble code (DTC) for lost communication when traveling, a diagnostic trouble code (DTC) for low battery voltage and a diagnostic trouble code (DTC) when a learn sensor is not obtained during the current operating cycle. Diagnostic trouble codes (DTCs) are also stored if the configuration of the system is not carried out, fails or is interrupted.
When a diagnostic trouble code (DTC) is stored, the ID number of the sensor that applies to the diagnostic trouble code (DTC) is also stored. When a diagnostic trouble code (DTC) is stored, a message is shown in the driver information module (DIM).

Configuration of the TPMS system
The TPMS system is self-learning. This means that when the vehicle is driven and the sensors transmit messages, the Central electronic module (CEM) receives and registers the ID numbers that the sensors transmitted.
After a process of elimination during a certain period, the Central electronic module (CEM) then decides that the sensors with the four most frequently received ID numbers belong to the vehicle.
There are two diagnostic procedures that can be activated from the diagnostic tool to make the system fully functioning from the factory or if any remedial actions has been carried out at the workshop.
- EOL test (End Of Line, factory test). The procedure is run after the ID number has been programmed in the vehicle. The purpose of this is to check that the entire chain with receiver, Central electronic module (CEM) and Driver information module (DIM) function and that the vehicle can receive transmissions from the sensors when the last tests are run in the factory.
- WS test (Workshop test). The procedure is used to program new IDs to the Central electronic module (CEM) and to check that the system functions correctly. For example, when a sensor has needed to be replaced or if the Central electronic module (CEM) has been replaced.
The differences between the two procedures are that the factory tests only finish OK after the four sensor IDs that are already programmed have been received properly. The workshop test finishes OK as soon as the four sensor IDs have been received.

Note! During the workshop test, it is important to check that no other tests are running around the vehicle. There is a risk that a sensor ID from another vehicle is received by the vehicle being programmed.

Quick check of TPMS




The system can be checked using the diagnostic tool by activating a read out at the same time as activating the sensors using a special tool. The special tool is positioned against the tire, where the sensor is located, at the same time as a button is pressed on the special tool. The special tool transmits a signal that activates the sensor so that it starts transmitting signals to the central electronic module (CEM). The activated sensor's ID number and tire pressure is then shown in the display in the diagnostic tool.

Note! The special tool for TPMS on S80 (-06)/S60/V70/XC70/XC90 does not work with the sensors on S40 (04-)/V50/C30/C70 (06-).