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Objective: Increase the functionality of the
current BMW OEM alarm system on the E46 without spending a fortune
on aftermarket alarms. I got inspired by a thread on another forum
and I did it today. Took no more than 15 minutes.
BMW Alarm is a single stage system, there is no warning stage. So I
got a single stage 3-wire shock sensor (found on ebay and local
electronics shops)
Sensor has 3 Wires:
1 Positive (Red)
1 Ground (Black)
1 Signal (Green - may differ from sensor to sensor)
DIY is simple. All the moding is done in the area of the brake fluid
reservoir.
!!Disconnect the battery!!
1. Connect the red (positive wire) on the battery positive terminal
under the hood
2. Connect the ground (black wire) on the ground screw in the brake
compartment.
3. Connect the signal wire on the pink/green wire that goes in the
limit switch that triggers the alarm when hood is opened.
4. Stick the sensor on the chassis metal using ultra strong 3M tape
Connect the battery!
When the shock sensor is activated, it uses the limit switch of the
hood to send a signal to the alarm system which is then activated
*thinking* that the hood has been tampered.
Simple - Easy - and you don't spend a fortune! The sensor I got has
adjustable sensitivity so I set it to activate when I hit not very
hard the rear window. Provides a level of extra security IMO.
The area of work
Sensor mounting point
Positive battery connection point
Pink/Green is the wire that you need to attach
the sensor wire to. Don't confuse it with the brake fluid wire. You
want the wire that goes in the hood switch
Sensor closer
A simple yet effective way to improve your
alarm! |