Joined: March 11, 2002 Location: Pennsylvania, United States Posts: 1,665
Posted: January 08, 2008 at 8:35 AM - IP Logged
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. ___________________________________ C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
Joined: March 11, 2002 Location: Pennsylvania, United States Posts: 1,665
Posted: January 09, 2008 at 9:11 AM - IP Logged
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. ___________________________________ C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
Joined: November 06, 2006 Location: Alberta, Canada Posts: 123
Posted: January 12, 2008 at 6:25 PM - IP Logged
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 .
Joined: March 11, 2002 Location: Pennsylvania, United States Posts: 1,665
Posted: January 14, 2008 at 4:03 PM - IP Logged
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.
___________________________________ C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum
Member List
Search
Register
Login
Topic: Key immobilizers and remote starting 
Topic Closed)
