Magazine for the auto service professional
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22 | September/October 2014 overnight in relation to the parked vehicle. Parasitic draws also can affect the battery in the remote key fob. If routinely stored within the reception range of the vehicle, the fob battery may prematurely die. Another potential concern relates to plastic proximity cards. If the card is stored next to a cell phone (in the driver's pocket, for example), it may be possible for the cell phone to erase or "scramble" the program in the card. While not a common occurrence, this is simply another potential concern to be aware of. Again, vehicle system designs vary. Some owners' manuals advise against storing a smart key in close proximity to various electrical devices where certain fre- quencies/felds may affect the key, such as TV sets, battery chargers, lamps, etc. Wireless ignition Chrysler's newer vehicles have gone wire- less. One of the new systems is the Wireless Ignition Node (WIN). This system uses a transponder remote keyless entry fob integrated key (FOBIK) which replaces the traditional metal key. With all of the func- tions of a traditional remote keyless entry fob, this unit also has a metal key blade for valet functions to lock the glove box and to open the door in the event of a dead battery, a remote keyless entry failure or a Bus fail- ure. This unit serves as the remote keyless entry fob and the electronic ignition key. The functions of the WIN are: – Sentry key immobilizer (SKIM) – Wireless receiver for remote keyless entry – Brake transmission interlock (BTSI) – Clock master – Steering column lock interface (BUX) for export only – Tire pressure monitor (TPM) system – Remote starting – Electronic ignition switch When entering the vehicle, the FOBIK is used to open the door locks and disarm the alarm system via the remote keyless entry. The FOBIK is then inserted into the WIN, much like an ignition key. But the similarity ends there. When the FOBIK is near the WIN, it transmits a secret key code via radio frequency to the WIN which in turn passes this information on to the controller area network (CAN). The WIN is hard wired to the CAN C Bus. The signal is then sent to the powertrain control module (PCM). At this point, if it is a valid key, the immobilizer is satisfed and the vehicle is ready to start. The signal is then passed through the central gateway on the vehicle, usually the Totally Integrated Power Module (TIPM). This information is then gathered by the other controllers via the CAN B, the CAN Interior High Speed (IHS) or in some cases the Locale Inter- face Network (LIN) Bus. Once the FOBIK is turned to the "start" posi- tion in the WIN, the WIN again transmits a mes- sage on the CAN Bus for starter engagement and when it returns to the run posi- tion, the "ignition on" functions through the PCM and the central gateway to the other modules. The WIN then monitors the tire pressures over the bus and provides the BTSI function via a hard wired input from the shifter assembly and brake switch. The system became available on some 2007 vehicles and was standard on all Chrysler, Dodge and Jeep vehicles by 2009. Immobilizer systems An immobilizer system prevents unau- thorized engine start unless the correctly programmed key is inserted into the igni- tion or remote/proximity unit is inside the vehicle (in the driver's wallet, pocket, laying on the console, etc.). The "smart key" is recognized by a radio signal, received by one or more antennas built into The Tech Bench Proximity cards (for specifc makes/models) are now avail- able in a very thin design, allowing storage in the driver's wallet. Shown here is a prox- imity card for a Lexus 600HL.