Today’s key fobs/smart keys provide convenience -- and cause problems

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Today’s key fobs/smart keys provide convenience -- and cause problems

In these days of vehicle owner expectations for their vehicles to perform tasks that would previously require a minor physical or mental effort on their part, the remote “key” has become a mainstay of late model design. Rather than inserting a metal key into a tumbler lock (obviously a task that requires far too much effort and manual dexterity), we now expect to press a button on a wireless transmitter to perform this arduous chore of locking or unlocking the vehicle doors.

Push-button ignition switches have also become commonplace, eliminating the need to rotate a mechanical key in an ignition switch cylinder.

Enter the wireless “remote” key fob, “smart key,” proximity fob or proximity card. Depending on vehicle make/model/year, this may look like a traditional “fob,” or a thin plastic card, similar to a credit card.

Note that a transponder key is not the same as a proximity fob/card. A transponder key features a small “chip” inside the key head that sends a signal to the signal amplifier and in turn to the ECU. This disengages the immobilizer system and allows engine starting. A proximity fob, or proximity card, merely needs to be in the range of the system in order for the system to allow engine starting via a push button ignition switch.

‘Smart’ keys

Call them what you will: keyless entry, smart keys, proximity keys, proximity fobs or cards, etc.

The car makers have been on a binge of offering “advanced” features relative to the unlocking/locking of doors, control of windows, moon roofs, mirrors, seat adjustment, radio presets, and remote engine starting via key “fobs” that are carried on the driver’s person.

A plethora of labels have been given to these gadgets. Following are the names for these systems per car brand.

Acura: Keyless Access System

Audi: Advanced Key

BMW: Comfort Access

Cadillac: Adaptive Remote Start and Keyless Access

Dodge: Keyless Enter-N-Go

Ford: Intelligent Access with Push-Button Start

General Motors: Passive Entry Passive Start (PEPS)

Honda: Smart Entry System

Hyundai: Proximity Key

Infiniti: Infiniti Intelligent Key with Push-Button Ignition

Jaguar: Smart Key System

Jeep: Keyless Enter-N-Go

KIA: Smart Key System

Lexus: SmartAccess System

Lincoln: Intelligent Access System

Mazda: Advanced Keyless Entry and Start System

Mercedes-Benz: Keyless Go

Mini: Comfort Access

Mitsubishi: FastKey

Nissan: Nissan Intelligent Key

Porsche: Porsche Entry and Drive System

Renault: Hands Free Keycard

Subaru: Keyless Smart Entry with Push-Button Start

Suzuki: SmartPass Keyless Entry and Starting System

Toyota: Smart Key System

Volkswagen: Keyless Entry and Keyless Start (KESSY)

Volvo: Personal Car Communicator (PCC) and Keyless Drive

An example of a keyless remote with proximity sensor is found in 2014 Honda models (their “Smart Entry System”). When the remote is on the driver’s person, and is within 32 inches of the driver’s door, the system senses an “OK to unlock” mode. As soon as the driver touches the driver door handle, the door unlocks (note that wearing gloves may prevent or delay door unlocking).


Once in the vehicle, the driver steps on the brake pedal (or clutch in a M/T car) and presses the start button to fire the engine.

If the remote’s battery is dead, the engine may still be started by pushing the start button several times (or pressing the button steadily) until a green light in the button flashes. Then touch the remote to the start button. You’ll hear a tone alert. Press the start button within 10 seconds to start the engine.

If the remote is left inside the vehicle, the doors will not lock after the driver has exited the vehicle. This prevents the remote from being locked inside the vehicle. The engine may be shut off by quickly pressing the start/stop button two times quickly or by holding the button in for 1.5 seconds.

Slight parasitic draws can pose a problem. While the vehicle’s system will (or should) go to sleep after a specified time (after the vehicle has been shut off, parked and exited), the proximity of the smart key to the vehicle can result in the possibility of a dead battery if the smart key remains in close proximity to the vehicle.

For instance, if the vehicle is parked close to a house, where the driver’s smart key or proximity card is stored within the design range of the system (for instance, with the smart key in a purse or wallet that’s within the key’s transponder range). If the system is constantly kept “awake,” this parasitic draw can, depending on the circumstances, result in a dead vehicle battery.

If a customer has a recurring issue of a drained battery, make it a point to ask about where the smart key is stored 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 frequencies/fields may affect the key, such as TV sets, battery chargers, lamps, etc.

Wireless ignition

Chrysler’s newer vehicles have gone wireless. 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 functions 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 failure. 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 satisfied 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 Interface Network (LIN) Bus. Once the FOBIK is turned to the “start” position in the WIN, the WIN again transmits a message on the CAN Bus for starter engagement and when it returns to the run position, 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 unauthorized engine start unless the correctly programmed key is inserted into the ignition 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 vehicle. Most vehicles outfitted with a smart key system will include a mechanical backup key. After exiting the vehicle, doors are locked by either pressing a button on the door handle, touching the door handle’s capacitive area, or in some models, by simply walking away from the vehicle (as the smart key recognizes a specific distance away from the vehicle, the doors lock).

An engine immobilizer system uses a transponder chip in the ignition key (or remote fob). The system features a transponder key ECU assembly that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the system’s ECU sends a signal to the primary ECM to prohibit fuel delivery and ignition, effectively disabling the engine.

Citing Toyota systems as an example, system components include a transponder key coil/amplifier, an unlock warning switch assembly, a dedicated system ECU and a security indicator.

The transponder key coil receives a key code when the key is inserted into the ignition key cylinder. The ID code is then amplified and outputs the code to the transponder key ECU.

The unlock warning switch assembly detects if the key is in the ignition cylinder and outputs results to the transponder key ECU.

The primary ECM receives ID verification results from the transponder key ECU. The ECM also verifies the immobilizer system’s ECU, allowing fuel and spark delivery.

When the transponder key ECU assembly detects that the key unlock warning switch is ON, the ECU provides current to the transponder key coil and produces a faint electric wave. A transponder chip in the key receives this wave, and sends a key ID code signal, which is sent to the ECU.

The ECU matches the key’s ID code with the vehicle’s ID code (previously registered in the ECU), and sends the results to the primary ECM using SFI communication.

Audi remote key communication

This TSB applies to all 2000-2010 Audi models. Potential issue: central locking via the remote control doesn’t work either sporadically or permanently, but the locks can be operated manually.

Missing synchronization between the remote control key and the vehicle can occur if the battery has been disconnected or if the battery in the remote control has been replaced.

If other senders operate in the same frequency range (mobile phones, TV stations, wireless headphones, baby monitors, other vehicle remote controls, etc.) the remote control key may have been temporarily switched off because a clear identification of the remote control key is not possible. This is necessary to prevent an unintentional unlocking of the vehicle by other unrelated senders.

A4 (8D, 8E, 8H) 2000-2008:

  1. Open the vehicle mechanically with the key.
  2. Press the unlock button of the remote control key.
  3. Insert the key into the ignition lock and switch the ignition to the ON position.
  4. Switch the ignition OFF again and remove the key.
  5. Press the unlock button or the locking button of the remote control key.

NOTE: Model year 2002 or later: If the synchronization procedure was not successful, adapt the remote control key(s) to the Central Comfort System control module (address word 46) using the VAS scan tool. Follow test plan J393-central control module for comfort system, adapting remote control key via adaptation (channel 21). Sometimes following the “erase all memory positions first” test plan produces better results.


A3, A6 (4B), TT, TTR:

  1. Press one of the buttons of the remote control key.
  2. Lock or unlock the vehicle once, mechanically with the key.
  3. The complete process must take no longer than 30 seconds.
  4. If the synchronization procedure was not successful, adapt the remote control key(s) to the central comfort system control module as described earlier.

A4 (8K) 2009-2010, A5 (8T) 2008-2010:

  1. Press a button on the remote key within the range of the vehicle.
  2. If necessary open the vehicle with the emergency key on the door lock.
  3. Switch the ignition on and off.

A6 (4F), A8, Audi Q7:

  1. Open the vehicle mechanically with the key.
  2. Insert the key into the ignition lock and switch the ignition ON.
  3. Switch the ignition OFF again.
  4. If the synchronization doesn’t help, check the battery of the remote control. The battery voltage must be 3.0V or above.
  5. If the battery voltage is below 3.0V, replace the battery and perform the synchronization again.
  6. Check whether there are any interfering senders in the vehicle.
  7. Check whether there are any interfering senders in the area.
  8. If interference was responsible for the condition, explain the technical background to the customer.
  9. If the synchronization procedure was not successful, adapt the remote control key(s) to the central comfort system control module (address word 46) using the VAS scan tool. Follow test plan J393-central control module for comfort system, adapting remote control key via adaptation (channel 21). Sometimes following the “erase all memory positions first” test plan produces better results.

GM power liftgate issue

Power liftgate will only work with RKE (remote control key fob)

Models: 2009-2013 Cadillac Escalade,

Escalade ESV

2009-2013 Chevrolet Suburban, Tahoe

2009-2013 GMC Yukon Models

(with Rear Power Liftgate (RPO E61)

The following diagnosis is helpful if the vehicle exhibits the symptom(s) described.


Some customers may state that the rear power liftgate is inoperative with the inside switch and the outside door handle. The customer may also state that when this happens, the power liftgate will work OK from the RKE key fob.


Starting in mid-model year 2009, GM changed the requirements for opening the power liftgate from the inside switch and the outside door handle. The change requires all the doors to be unlocked before opening the power liftgate. This can be accomplished by pressing the unlock button on the key fob twice or pressing the unlock button on the door panel. The change only applied to the power liftgate module when using the inside switch and the outside door handle.

The power liftgate will open at any time when pressing the power liftgate button on the RKE Fob.

Some 2009 Model Year vehicles that were built in calendar year 2008 may have older software and may not operate as described above. This may only be a concern if a customer compares this vehicle with a fellow neighbor that was built in calendar year 08. Both vehicles are built to factory specs and no parts should be replaced to change the operation of either vehicle.

NOTE: If a customer has a complaint where the power liftgate is inoperative, have the customer press the unlock button on the door panel and then see if the liftgate starts to work before starting with normal diagnosis.

Follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Technology makes people forget

Since remote controls, remote-control key fobs or “smart” keys are becoming so commonplace, allowing door locking and unlocking with the press of a button, the mechanical lock cylinder in the door(s) generally becomes unused and ignored.

As a result, when/if the remote fails to operate, due to a dead remote control battery or other glitch in the system, if the driver then attempts to unlock the driver door using the mechanical key, the lock cylinder may be sticky or seized due to a lack of activity.

Before a vehicle leaves your shop, do the customer a favor by lubricating the lock cylinder and inserting and working the key to ensure that it’s operable if and when the need arises.

Even if the engine won’t start (due to a glitch in the remote key programming with a proximity key), at least the driver can enter the vehicle, safely out of the weather, and can then use their cell phone to call for assistance.

While technological advances provide convenience, they can also cause problems, by making drivers rely too heavily on electronic convenience and comfort systems to execute functions once performed by a physical effort. But, these systems are here to stay, and we need to understand how to deal with them.   ●

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