I found the instructions that came with my remote starter, for finding the proper resistance value in a passlock II system. With the key in and turned to the "on" or "run" position, put the car in reverse. Turn the key to the "start" position and the back to the "run" position. Now read the resistance between the black wire and the ignition side of the yellow wire. Putting the car in reverse, prevents the car from starting, while checking the resistance. Use a digital meter and take two readings, reversing the leads on the meter. If the readings are different, use the higher of the two. The resistance value of the resistor, you use, must be within 1% of the value. You may need to connect a series of resistors together to get the proper value. The wattage of the resistors isn't important the one's I used were 1/2 watt. I used the 20K setting on my meter to get the readings. An adjustable variable resister with a trimmer in the resistance range you need works well also, because you can dial it in to the exact resistance. Not sure if Radio Shack would have one though. That is how the remote start bypass modules set the resistance. The resitance for my Impala is 4.62K.