by Bruce Murray

[This text is largely lifted from the Alfa 164 TSB #40.95.02 but includes a drawing and picture that show the current (1999,2000,….) transmitter being supplied by Alfa.]

The ALARM ECU is located in the trunk, on the left rear wheel well, under the carpet. It is designed to recognize a RF (Radio Frequency) code sent by the remote transmitter. The RF code number can be found printed on a sticker; 1) inside the remote transmitter, or 2) inside the alarm ECU. The RF code is made up of the letter "A" & three digits, plus the letter "B" & three digits, for example A227B264.

A remote transmitter can be programmed or "coded" by opening the case, removing the circuit board, and bridging the appropriate chip pins to a solder strip using a low wattage soldering iron. There are two solder strips, one for the "A" code strip and one for the "B" code strip. Each chip pin has a numeric designation that, when choosing the proper ones, will numerically add up to the code. See below for an example of how to decipher a code.

To determine which pins should be "bridged", you must perform a series of mathematical calculations. The results will indicate the appropriate pins. The pins have values of 256, 128, 64, 32, 16, 8, 4, 2, and 1. Only these numbers are used in the calculations below:

Our example: Code A227B264. Starting with the "A" part of the code (227):

1) Find the largest value below 227 (in this case 128) and subtract it to get 99

2) Take the 99 result and subtract from it the largest possible value (64) to get 35

3) Take the 35 result and subtract the largest possible value (32) to get 3

4) Take the 3 result and subtract the largest possible value (2) to get 1

5) Take the 1 result and subtract the largest possible value (1) to get 0

Thus the pins to be jumped to strip A are 128, 64, 32, 2, & 1 (which miraculously add up to 227).

After you have broken the code down to "0", you will solder the pin numbers that you identified using the above subtraction method to strip A or B. Obviously, use strip "A" for the "A" code & strip "B" for the "B" code. In this case, you would solder pins 128, 64, 32, 2 & 1 to strip "A". Now repeat this same mathematical procedure for the "B" part of this code. In this case you would find that B264 would break down to pin 256 and pin 8. You would solder both of them to strip "B".

• Note really well: The 128 and 256 value pins are in reverse numerical order compared to the rest.