This is a VATS System:
This system uses a resistor in the key, use a digital volt meter set to ohms and put 1 lead on each side of the vats chip in the center of the key, find a resistor to match your reading.
Locate the Orange or Black tube running down the steering column from the ignition switch. Cut open the tube to epose the passkey wires insie. Your resistor or trumpet should be within +/- 10 ohms of the key. Either of the passkey wires can be cut. GM uses only a fixed number of different resistors with their PASSKEY/VATS system, your measurement should correspond to one of the following values.
390 Ohms | 1470 Ohms | 4750 Ohms |
520 Ohms | 1800 Ohms | 6040 Ohms |
680 Ohms | 2370 Ohms | 7500 Ohms |
885 Ohms | 3010 Ohms | 9530 Ohms |
1130 Ohms | 3740 Ohms | 11800 Ohms |
This is a Passlock I & II system:
In 1996 GM introduced the GM Passlock anti theft system. When a GM vehicle is equipped with the Passlock system, adding a remote car starter requires that the GM anti theft system is temporarily bypassed or disarmed. The Passlock passive antitheft security system resembles in some ways the GM V.A.T.S (Vehicle Anti Theft System) because it also uses resistor codes which must be authenticated by the Anti Theft security system in order to start the engine.
The Passlock Anti-Theft system involves resistor codes which are generated by resistors located in the ignition key cylinder switch. The GM Passlock system uses what is known as a Hall Effect Sensor to send a resistor code to the Passlock module. The resistor code is activated when the ignition key is physically rotated in the ignition switch. Depending on the model of GM vehicle, the actual resistor code is only introduced to the Passlock system when the ignition switch is turned to the ignition on (run) position or only when the ignition switch is turned to the start (crank) position.
The advantage of this technology is significant since the management system controls the fuel injection, timing and performance of the engine. An invalid resistor code allows the management system to completely close down the motor vehicle engine. This technology offers good basic engine immobilizing features for the general population. GM has developed a more sophisticated system called Passkey 3. Passkey 3 is a transponder (RFID) immobilizer system which offers major improvements over the Passlock and VATS anti theft systems because communication between the sensor of the key and the engine management system is accomplished by a system of codes dependent on the value of the ID transponder so that thieves cannot simply cut appropriate wires and bypass the communication system.
In all cases GM advanced vehicle security means adding a remote car starter to a vehicle equipped with a VATS, Passlock or Passkey type anti theft system is much more involved. To this end we have developed a complete line of installation kits that allow you to TEMPORARILY bypass the vehicle anti theft system when remote starting your vehicle. It doesn't matter what kind of car starter brand, these kits will work with ANY make or model remote car starter.
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA