Bypass & Interface Modules

Recently new and late model vehicles have factory anti-theft systems (immobilizer systems) to prevent a vehicle being started without the owner’s specific “coded” key in the ignition. Most vehicles have a “transponder chip” embedded in the head of the ignition key. When the “coded” key is inserted in the ignition switch the transponder code is sent to the vehicle’s immobilizer system enabling the vehicle to be started.
These OEM anti-theft systems are valuable to the vehicle owner by helping to prevent a crook from hot-wiring and starting your vehicle. Without the “coded” key, the starter will crank, but the immobilizer prevents the engine from being started. Of course, these systems will also prevent a remote starter from starting your vehicle because there is no key in the ignition.

There are two ways around this:
– Leave a key in the ignition, which could easily result in your vehicle being stolen.
– Install a Bypass/Interface Module which is then uniquely programmed to your vehicle so that the module sends the transponder code to your vehicle’s immobilizer system when the remote starter is activated.
Either way (with a key in the ignition or a bypass / interface module programmed to the vehicle), the required transponder code is sent to the vehicle’s immobilizer system enabling the vehicle to start and run.

Each vehicle manufacturer has their own unique anti-theft immobilizer system(s). Chrysler, Ford and GM have improved their anit-theft system in recent years. GM has progressed from the VATS system, to Passlock I, Passlock II, PassKey 3, Passkey 3+, etc. Ford from PATS to SecuriLock, to SecuriLock Encrypted, etc. Chrysler from Sentry-Key 1st Generation to Sentry-key 2nd generation, etc. Because of these improvements to the systems you need to know the make, model, and year of the vehicle to determine the specific bypass/interface module needed to enable your vehicle to be remote started.
Here are just a few examples of the various ignition keys …

gmkeybThe GM VATS (Vehicle Anti-Theft System) was one of the first OEM anti-theft Systems. It has a visable “Resistor” embedded in the key shaft. The resistor must match the VATS Resistance in the vehicle’s VATS Module to enable the starter to crank.

toyotakeybThis Toyota key has a plastic head, but no transponder chip embedded in the plastic because this vehicle does not have an anti-theft immobilizer system. So, sometimes you cannot tell if the vehicle has an anti-theft immobilizer system just by looking at the key.

hondakeybThis Honda key has the keyless entry built into the key and there is a transponder chip embedded in the plastic. Some Honda keys have only a plastic head, but also with a transponder chip embedded in the plastic. Either key starts the vehicle. This vehicle has an anti-theft immobilizer system. there is also a “security” light on the dash that lights when the key is inserted in the ignition and turned on.

bmwkeybThis BMW Key has a plastic head with a transponder chip embedded in the plastic. This vehicle has an anti-theft immobilizer system, as do most recent year BMW vehicles.

Directed Electronics, Inc (DEI), is the world leader in remote start technology and factory interface systems.
Following are some of the early anti-theft immobilizer systems and the “Bypass Modules” DEI developed to enable the vehicle to be remote started.

DEI 652T VATS Kit consisting of a set of the 15 resistors that matched the GM VATS System. There were only 15 different resistors used in the manufacture of hundreds of thousands of GM vehicles. Installation required measuring the resistance of the resistor in the VATS ignition key, and then building a bypass system using a relay with the matching resistor. Activating the remote starter, activated the relay, and sent the matching resistance to the vehicle’s VATS decoder enabling the engine to crank.

DEI 555U Universal Bypass Module that uses one of the vehicle’s coded transponder ignition keys permanently inserted in the Bypass Module. The Module reads the key code and sends it to the vehicle’s immobilizer system enabling the vehicle to be started, very similar to having a key actually in the ignition.

DEI 555T Bypass Module for GM vehicles with Passlock I or Passlock II Immobilizer Systems. The GM passlock Systems had about 2,000 different resistors used in the manufacture of GM vehicles. A huge anti-theft improvement as compared to using only 15 different resistors as in the VATS system. The 555T Bypass Module could be programmed to match the vehicle’s passlock resistance, enabling the vehicle to be remote started.

Vehicle manufacturers have developed more and more sophisticated anti-theft immobilizer systems to reduce auto thefts. The vehicle’s have also become more sophisticated in electronics including door locking systems, starter systems, smart keys, push-to-start, etc. Consequently DEI has developed more and more sophisticated Bypass & Interface Modules to enable vehicles to be remote started and also to interface with the vehicle’s sophisticated electronics.

Today, there are basically three (3) types of Bypass and Interface Modules:

Bypass Only Modules. Designed only to handle the vehicle’s immobilizer system to enable remote starting.
Door Lock & Factory Alarm Interface Modules. Designed to interface with the vehicle’s door locking system and to disarm the factory alarm. Generally used for installing Security Systems and/or Keyless Entry Systems.
Combination Bypass & Door Lock Interface Modules. Designed to handle the vehicle’s immobilizer system and the door locking / factory alarm system with one integrated module.

Many vehicles have several (numerous) choices of Bypass and Interface Modules because of the continual development of more sophisticated, and easier to install, modules by DEI. What you choose depends on what you are trying to accomplish.

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