2015-07-19 (Su) RFID Car Access

After success with the RFID reader, plans were made to install the device into a car. 1999 Toyota Avalons used a built-in security system which prevented the unlock button from being pressed after the car was locked. Only a key or remote could unlock the car without triggering an alarm. Modifying a remote was chosen as the easiest method. It may have been possible to manipulate something in the door but there was a spare transmitter.

After opening a transmitter the button terminals were mapped with a continuity tester. Unfortunately no convenient access points were found for the buttons so wires were soldered to the switch terminals. This approach should work for most remote units. Small wires with very little exposed wires were used and a sharp soldering iron tip were crucial. Two wires were run which corresponded to the switch terminals and could be touched together to emulate a button press.

Opened remote module

Continuity tester next to module

Wires soldered to switch terminals

Auto stores stock 12v mechanical relays which are capable of carrying up to 30amps. Remote key fobs do not exceed a few milliamps so a much smaller relay would be capable of the job so long as it was a 12V mechanical relay. Fuse taps can also be found at many auto stores. Fuse taps allow a new circuit to be run from the fuse box without cutting any wires. A crimper was necessary and a good tool to have.

Relay with wiring diagram

Fuse tap

Wires were lengthened on the commercial RFID unit to reach the car's fuse block. Longer wires allowed the control unit to be placed on the dash of the car along with the rest of the parts to consolidate things. An enclosure will be necessary to hide the parts.

Wires run along dash seam

Outside view

To do:
  • Interface with remote unit
  • Add circuit to car
  • Install device
  • Add enclosure

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2

This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

2015-07-18 (Sa)