I'm going to attempt here as comprehensive an explanation as I can regarding immobilizers and what you need to know about them when
installing or
purchasing a remote start.
Note that I'm
not referring to factory alarm systems in this post. Although they sometimes interfere with remote starting, immobilizers are the much more common issue.
Types of Immobilizers
1. GM Passkey I/II or VATS type:
Passkey I was the first passive immobilizer, introduced on the 1986 Corvette. It uses a special ignition key with a visible resistor pellet (easily recognizable when compared to conventional keys); there is also a decoder in the car which recognizes the resistor in the key and enables fuel and/or cranking. Passkey II differs slightly in some of the hardware on the car. These have been used as recently as the 2004 Buick Century/Regal and Corvette.
2. GM Passlock I/II type:
Passlock uses a resistor, like Passkey; however the resistor is located inside the ignition key cylinder, and the resistor code is sent once the key cylinder is turned to the crank position. Despite having an immobilizer, Passlock ignition keys are no different from conventional ignition keys. Passlock was introduced on the '95 Chevy Cavalier/Pontiac Sunfire and used on many GM models through 2007.
3. Transponder type:
A transponder-based immobilizer involves an antenna ring around the ignition key cylinder, and specially programmed keys. When the ignition is turned on, this antenna sends a signal and looks for the key to repeat a signal back to it; if it does not receive a valid key signal then fuel and/or cranking are not enabled. Some transponder keys are very distinctive in appearance(such as Chrysler's gray older model SentryKey), some really aren't(such as GM's Passkey3). Transponders have been in automotive use since 1995 and are standard equipment on the vast majority of new cars sold today.
Immobilizers and Remote Starting
A remote starter is designed basically to electrically connect wires from a car's ignition switch, in the same way that they would be connected by a driver starting the car with the key.
Since just connecting those wires isn't enough to start an immobilizer-equipped car, aftermarket remote start installers have been forced to find ways to temporarily bypass factory immobilizers when a remote start is activated. Most times this is done by a part specifically designed for bypassing an immobilizer, although Passkey I/II and Passlock I/II can be bypassed with relays and resistors.
There are too many brands and models of bypasses to list here, so I'll just explain their general means of operation.
Bypassing specific immobilizer systems:
Passkey I/II, Passlock II -
Almost every security manufacturer who makes a bypass will have one available for these systems. They are quite common and are connected close to the remote start connections.
Passlock I('95-'99 Cavalier/Sunfire, '96-'98 Grand Am/Olds Achieva/Buick Skylark), and special late model Passlock('03-'07 Saturn Ion, '04-'07 Chevy Colorado/GMC Canyon/Isuzu I-series, '05 only Chevy Cobalt) -
These cars also have bypasses available for them; however some bypasses which are designed for Passlock II will not work, so it's important to ensure that the bypass used says that it's compatible with these cars.
Transponder-based systems -
Generally there are 3 types of bypasses for a transponder-based system.
Type 1 - "Universal" Bypass. This involves a box into which one of the vehicle's keys is placed and mounted under the dash. When the remote start is active, the signal from this key travels through a ring around the key cylinder into the factory antenna.
Pros:
- Work on many different vehicles
- Fewer wire connections to car
Cons:
- Takes a key away
- Sensitive to cold temperature
Type 2 - Vehicle-specific RF Bypass. This works basically the same as the universal bypass, except that it includes a chip designed to program to the car like a key would (thereby not sacrificing one of the car's keys).
Pros:
- Few wire connections to car
- Doesn't use an extra key
Cons:
- Sensitive to cold temperature
- Not available for all vehicles
Type 3 - Vehicle-specific Data Bypass. These types have become available in the past 5 years and involve connecting to wires on the car. They send a data signal directly to the car's computers to enable starting.
Pros:
- Reliable in all temperatures
- Doesn't use an extra key
Cons:
- Not available for all vehicles
- Requires more wire connections to car
I hope this helps everyone understand things a bit better. If anyone thinks I should go into more detail about anything here please post a reply or PM me.
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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
good read and very much information available for the new installers. This should be a sticky. well cheers and props to you chriswallace187
Ok...I'm not seeing the edit button here, but I'd like to add to my initial post that Passkey I/II and VATS are interchangeable terms as far as this post goes.
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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
you cant edit the post after 24 hours or something.
PassKEY II has a resistor in the key. PassLOCK II does not - it has a resistor located in the ignition lock cylinder on the car.
Passlock ll systems use different strength magnets located within the ignition lock cylinder , as the two magnets rotate past a Hall effect switch , the magnet strength is read and compared to a stored value in the PCM .
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so technically, you can start a passlock 1 car with a flat head
tedmond wrote:
so technically, you can start a passlock 1 car with a flat head
Ehh...if you were a good enough lockpicker to turn the key cylinder without a key you could do that...according to a tutorial from one of my marine buddies who used to steal cars for fun that's more work than is necessary on most older cars: the key cylinder is easy enough to just remove entirely.
Assuming your typical amateur thief (the only type who's going to be stopped by an immobilizer) does that, the IPC or BCM isn't going to ever receive an R-code and the car won't start.
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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
chriswallace187 wrote:
tedmond wrote:
so technically, you can start a passlock 1 car with a flat head
Ehh...if you were a good enough lockpicker to turn the key cylinder without a key you could do that...according to a tutorial from one of my marine buddies who used to steal cars for fun that's more work than is necessary on most older cars: the key cylinder is easy enough to just remove entirely.
Assuming your typical amateur thief (the only type who's going to be stopped by an immobilizer) does that, the IPC or BCM isn't going to ever receive an R-code and the car won't start.
most GM with passlock 2 first generation (1998 to 2002) for trucks and (2000 to 2004) for cars, can be bypassed with 2 diodes very easily.
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j-marc
Not sure what you're referring to jmroussel - where would you connect the diodes to in order to bypass Passlock 2?
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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
any one famiiliar with the relay style of bypassing transponder? if so my question is do you think its easier to steal the car with the relay setup ? rather than the module?
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IMMIGRANTS ARE LIKE SPERM MILLIONS GET IN BUT ONLY ONE WORKS.
It depends on how well the key is hidden - it's obviously a lot easier to conceal a key inside a black box than one in the open, with wires plainly wrapped around it.
If the key could be well concealed and relatively hard to get at, and the wires to it look relatively close to the OEM wiring, it wouldn't be a big deal.
IMHO the best solution is to avoid the issue entirely by using a bypass that doesn't require a key.
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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two