BMW E46 3 Series DIY

MOD NAME: Alarm Shock Sensor install
MOD COST: $10.00
MOD BENEFIT: Increase the functionality of OEM Alarm
MOD DESCRIPTION (PICS OR FAIL)

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

Write up by: paris

Copyright: Paris Argyrides

A simple yet effective way to improve your alarm!Wr