PASS-Key bypass module instructions

The PASS-Key bypass module is designed to bypass the vehicle theft deterrent system on certain GM engine control systems by generating a fuel enable signal. This module will work for systems that require a 30 or 50 hertz signal on a dedicated fuel enable wire to the ECM/PCM. It will not work with systems that use a fuel enable password that is transmitted on a serial data line to the ECM/PCM. It will not bypass the starter interrupt relay found on some vehicles. The intended use for this module is in engine swaps where the original theft deterrent equipment is non existent or not desired. It can also be used to reduce repair costs of non working systems and for troubleshooting no-start conditions. The most common symptom of a theft deterrent lock-out after an engine swap is when the engine will start and run for about 1 or 2 seconds and then shut off.

 The module needs just three simple connections. The red wire gets connected to a +12v switched power source. The module draws very little current and can be connected to any existing circuit, such as the ignition circuit for the ECM, normally a pink wire w/black stripe. The blue wire gets connected to the VATS/passkey fuel enable pin of the ECM, the pin number will vary depending on the vehicle. A listing of some common pin numbers will follow. The black wire gets connected to ground.

 The output frequency is selectable by moving a jumper as shown in the picture below. Most Pass-Key systems require a signal between 40-60 hertz. If you are unsure of the correct frequency, you can try both without doing any damage. The ECM will store a fuel enable error if the frequency is wrong. The Potentiometer is for calibration and should not need to be adjusted. If the potentiometer has been moved, it can be re-set using an oscilloscope or by using the following method. Turn the dial all the way in one direction. While cranking the engine, slowly turn the dial until the engine starts. Turn off the engine and mark the position of the dial. Turn the dial fully to the opposite direction. Crank the engine again and slowly turn the dial until the engine starts. Turn off the engine and mark the second position of the dial. Finally, set the dial at the midpoint between the two marks.

The following table lists some known compatible vehicles. Please verify the pin # for your application before connecting the module. The fuel enable wire should be dark blue. Email me with your specific year/make/model if it is not on the list.