Brief Description Of Components

The SMG system comprises the following key components:

4 Wheel Speed Sensors  The wheel-speed sensors of the Dynamic Stability Control (DSC) measure the wheel speeds of the individual wheels.

RPA button  (E46, E53, E83, E85) The RPA button is only needed for initializing the PRA.

(RPA initialization means "teaching the system the tire pressures".

CID: Central Information Display  Vehicles that are equipped with CID are initialized using the CID.

On-board computer button and rocker switch on turn-signal/main-beam switch  (E87, E90, E91) Initialization is performed on the LCD display, using the BC button and the rocker switch on the turn-signal/main-beam switch. The on-board computer functions are selected with the rocker switch.

The RPA software is in the following control units, depending on model series:

• RPA Control Unit  (E46 all-wheel drive)

  The E46 All-wheel drive has a separate RPA control unit.

  The 4 wheel-speed sensors measure the wheel speeds. The DSC control unit sends the signals through 4 direct wires to the RPA control unit.

Alternatively 

• DSC control unit with additional software for Run Flat Indicator  (E46, E53, E60, E61, E63, E64, E83, E85, E87, E90, E91)

  With DSC Mk60 and DSC 8, the RPA is integrated into the DSC control unit through additional software.

Alternatively 

• CIM: Chassis integration module  (E65, E66)

  The CIM controls:

  • Servotronic
  • Steering column adjustment
  • Run Flat Indicator (RPA)

The following control units are involved in the functions of the Run Flat Indicator:

• CAS: Car Access System  E60, E61, E63, E64, E65, E66, E87, E90, E91

  The CAS control unit provides input signals relating to terminal status (e.g. terminal 15 ON).

• GM: Basic Module  E46, E53, E83, E85

  The general module provides input signals relating to terminal status (e.g. terminal 15 ON).

• JBE: Junction Box Electronics  E87, E90, E91

  The JBE is the data interface (= gateway) between the K-CAN and the PT-CAN. (K-CAN stands for "Body Controller Area Network"; PT-CAN stands for "Powertrain Controller Area Network") The junction box consists of the junction-box electronics and the electrical distribution center.

• KGM: Body-Gateway Module  E60, E61, E63, E64 from 09/2005

  The body-gateway module replaces the safety and gateway module (SGM). The KGM forms the data interface (= gateway) between the K-CAN and the PT-CAN.

• M-ASK/CCC: Multi-Audio System Controller/Car Communication Computer  The M-ASK/CCC will emits an acoustic warning through the loudspeakers if tire pressure drops. (On vehicles without M-ASK or CCC, the instrument cluster will emit the warning.)

• SGM: Safety and gateway module  E60, E61, E63, E64 up to 09/2005 E65, E66 from 03/2004

  The SGM is the data interface (= gateway) between the K-CAN, byteflight and the PT-CAN.

• SZL: Steering Column Switch Cluster  E87, E90, E91

  The signals from the on-board computer button and from the rocker switch are recorded and processed in the SZL. The data are transmitted to the instrument cluster through a direct wire (on-board computer).

• ZGM: Central Gateway Module  E65, E66 until 03/2004

  The ZGM forms the data interface (= gateway) between the K-CAN and the PT-CAN.

• KOMBI and CID:Instrument Cluster and Central Information Display  A fault in the RPA or drop in tire pressure will be indicated by the RPA indicator and warning light in instrument cluster. At the same time, the symbol will light up in the LC display.

  Faults registered by the RPA are indicated as follows by the RPA indicator and warning light (for variations, please refer to national version):

  • The RPA indicator and warning light lights up:
    • Red (with acoustic signal):  Drop in tire pressure more than approx. 30 % +/- 10 %. Driving safety is no longer guaranteed.
    • Yellow:  RPA failed

Information about the Check-Control message can be called up in the CID (CID is fitted depending on the vehicle's equipment).

RPA Indicator And Warning Lights And Central Information Display 

Installation Location

The Run Flat Indicator (RPA) has the following displays in the instrument cluster:

• RPA Indicator And Warning Light
• Symbol In LC Display

Fig 1: Identifying Runflat Indicator (E83 Shown)

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Identifying RPA Warning In Central Information Display

Courtesy of BMW OF NORTH AMERICA, INC.

How It Works  RPA fault is displayed as follows:

• Via the RPA indicator and warning light The RPA indicator and warning light lights up:
  • Red (with acoustic signal):  Drop in tire pressure more than approx. 30 % +/- 10 %. Driving safety is no longer guaranteed.
  • Yellow:  The RPA has developed a fault.
• Indicator or symbol in LC display (yellow or red).
• Check control message in Central Information Display (CID) with additional information text.

If the RPA should fail, the following Check-Control messages are possible (for example):