Tire Monitoring System - System Diagnostics
44 08 082016525/3
November 4, 2008. Supersedes Technical Service Bulletin Group 44 number 07-06 dated December 6, 2007 for reasons listed below.
Vehicle Information
44 TPMS diagnosis A4 (B7), A6 (C6), & Audi Q7
Condition
Helpful information for diagnosing BERU low-line modular tire pressure monitoring systems installed in A4(B7), A6(C6), and Audi Q7 models.
Technical Background
A tire pressure monitoring warning displayed in the instrument cluster does not necessarily mean that there is a fault. It could mean that the pressure in one or more tires is low, the pressure in one or more tires needs to be adjusted, or the proper procedure for correcting low pressure or changing wheel sets was not followed.
Always explain to the customer that when TPMS warnings are displayed, it is important to first check all tire pressures and make any necessary adjustments as soon as possible. Description of the warning can be found in the Owner's Manual and should be referenced to distinguish between types of warnings. This is critical in order to properly diagnose TPMS concerns.
These are some of the common conditions that trigger a warning with or without DTCs:
- System sees a pressure loss in a least one of the tires.
- Control unit sees less than 4 sensors while the Wheel change procedure is being carried out or after the system has learned 4 sensors.
- Control unit sees more than 4 sensors while the Wheel change procedure is being carried out.
- Tire pressures adjusted without selecting Store curr. tire pressures afterwards.
- Aftermarket equipment (e.g. wireless headphones or garage door opener) which has the same frequency of 433 MHz as the TPMS is used in the vehicle.
- New wheels and tires installed without tire pressure sensors.
- Wheel change was selected but the required drive was not carried out.
Adjusting and storing tire pressures should be done as a courtesy to the customer and cannot be claimed under warranty.
Production Solution
No change.
Service
System basics
This system is equipped with only one antenna, which receives signals from each sensor and transmits them to the control module via LIN bus. Since there is only one antenna, this system does not recognize where each sensor is located on the vehicle; instead the control module only allocates 4 sensors to the vehicle. When the system is learning its sensors (Wheel change procedure)
The spare wheel and tire with a pressure sensor is not monitored by the system. The fifth wheel that does not rotate when the Wheel change procedure is carried out is recognized as the spare by the system and is no longer monitored after this point. All sensors, including the spare, can be triggered with VAS 6287 tool and checked in MVB 16.
Storing Tire Pressures
After Store curr. tire pressures is selected the system compares the actual tire pressures being stored with the coded value of the control unit (digits 3, 4, 5, & 6 of the coding). If the pressures being stored are below the coded value the system will stop the learning process, issue a warning in the instrument cluster, and the system status in MVB 17 will change. Coded value should equal the recommended partially loaded pressure stated in the Owner's Manual or the decal on the vehicle (location depends on the model and model year). Tire pressures should be stored when tires are cold or at ambient temperature. If pressures are stored when tires are hot/warm, they will drop once the tires have cooled and may drop below the minimum threshold and trigger a warning. On average, a temperature change of 10°F results in a pressure change of 1 psi or a temperature change of 10 degree C results in a pressure change of 0.1 bar.
Changing Wheels
Whenever a wheel is changed or a new sensor is installed the Wheel change procedure must be carried out, which requires the vehicle to be driven for at least 20 minutes at speeds above 24.9 mph (40 km/h). During this procedure the system learns all of the installed sensors and their pressures. Tire pressures are learned in the same manner as when Store curr. tire pressures is selected.
Antenna
Antenna mounting location varies based on the model. But in every application the antenna must be positioned so that it faces in the proper direction in order to receive all sensors (see ElsaWeb). Antennas are marked with which side should face the wheels.
"Diese Seite Richtung RAD" - This side towards wheels
An improperly mounted antenna will still receive signals from some of the sensors but it will not receive all 4 consistently. Also a lower limit not reached DTC will be stored, which means the control unit does not see 4 rotating sensors as it should.
If a TPMS warning is displayed with or with out a DTC being stored after the required test drive is complete, it is important to check the system status in MVB 17 (first 4 digits). The following are some of the common system statuses;
- 0049 - The tire pressure monitoring has been adapted successfully.
- 0149 - The tire pressure monitoring system is in the adaptation phase but the road test was probably aborted to early. The adaptation procedure must be readapted, or the adaptation procedure can be aborted by triggering the wheels using the hand sender.
- 0249 - The tire pressure monitoring system cannot be adapted. The specified pressures of the tires are not OK. Correct specified pressures, save them and then repeat adaptation procedure.
If a TACS case is initiated it is important to provide the latest system status value from MVB 17.
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Additional Information
More information on this system can be found in the following resources:
- Owners Manual
- ElsaWeb
- SSP: 993403
- TSB 2011237
- VAS Scan Tool
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service manuals for the latest information.