Opening and closing RF roof with a key fob

You can put the roof down while you approaching the car, how cool is this?

After successful implementation of the one-touch roof control module, next idea is to do this using a key fob from outside the car.

This is a very challenging task because the roof mechanism operates only when Ignition power is on. To solve this problem, I modified my ACC controller to control the IG relay instead. This module would listen to CAN messages and when activate IG relay when needed by pressing Lock or Unlock buttons on the key fob. After roof operation completed (which is also known as an event on the CAN bus) IG relay will be turned off. RF controller also can listen to CAN bus for key fob messages and activate mechanism when needed.

Quick implementation was successful, and I got everything working as desired. Because I already had Windows Controller installed, everything is fully functional. Technically windows controller could be optional, but if you leave windows down and then remotely put the roof up, there is no way to close windows without entering the car again. Also, in a US car after closing the roof, windows will leave a gap of 1″, which I can close remotely with one more click.

We tested it with RF 2017 and RF 2020, MT and AT versions.

This product will be available by end of June 2021 from our store.

“SmartTop” alternative

One of the most popular modifications for MX-5 RF is adding the “SmartTop” module made by mods4cars. This is a very simple electronic device, but it cost over $300, I think because there is no competition. I decided to design and produce my own version of such a device. Basically, it is just a CAN bus bridge, which can filter can messages, to trick the roof mechanism by blocking messages which will disable operation (like higher speed, car in reverse, etc). My previous project for the front camera kit has a similar design, so it was easy to reuse it for this project.

Implementing a one-touch feature is very simple as well, because the roof control switch produces only two voltage levels, to keep the roof opening or closing.

Another idea for this device is to be able to control the roof using the key fob like it is done in BMW Z4 for example. So you open the roof while approaching the car. This is quite a challenging task because the roof mechanism operates only when Ignition power is on and other modules on the CAN bus operational. I’m hoping to override these limitations by integrating the IG power switch for the roof controller in my device and substitute the CAN messages for initial communication.

My first version of this device now operational for all basic features. The software can be updated at any time via USB cable. To do this, my son made for me a Windows application.

Because I have to have communication with Key Fob, I found that it would be useful to have different configurations assigned for each key fob. If you need to give the car to someone else, you can share a key that has disabled the new feature, to avoid confusion at the service center for example. Or for valet parking, you can share the key with completely disabled roof control, so they can’t play with this feature.

Hardware installation will be exactly the same as for “SmartTop”, YouTube has tons of videos on how to do this.

The module it self 50mm x 59mm x 18mm. It has a Micro USB connector for programming, LED status and a 16 pin connector for the main harness, similar to “SmartTop” is using. This device with a harness will be available in my store for $159.

BlackVue 750X

The new product line from BlackVue 750X series has an integrated battery monitor for recording in parking mode. I installed 750X-2CH-32GB in my MX-5 RF under the rearview mirror.

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The rear camera attached to the wind blocker.

This camera set comes with a new power cable, with 3 wires to connect to battery power, ACC power, and ground. Unfortunately, the new power connector is not compatible with the previous 750S series. I modified supplied cable to connect it with a rearview mirror harness.

In parking mode, the camera can record in time-lapse mode or activated by an accelerometer. With a setting of the battery limit of 12.5V, I had 2-3 hours of time-lapse recordings.

I have a 32GB SD card option, with the highest quality settings it is enough for two hours of recording.

Measuring dark current.

Modern cars with lots of electronics always have battery drainage even the engine is off. Electronics will go to sleep mode, but it will still consume a little. I have designed many electronic accessories and decided to check if there is any effect on battery life. My test car is the 2017 Mazda MX-5 RF Launch Edition. It has a SmartTOP module installed as well as my front camera kit, ACC controller, and automatic footwell light.

Measuring current accurately is a little tricky because any circuit interruption will wake up all electronics again. Also range from 10A to milliamps. To avoid these issues, a circuit switch is really handy. I found a good option on Amazon. Because I’m often testing new electronics, I found that having this device installed is time-saving.

Now, when the switch is in position “Power on” I can safely attach the multimeter and after 2 minutes switch can be disconnected and a small current will go through the tester.

When car is unlocked, current stays about 100mA

The proximity of Key Fob seems to have no effect on this test, however when the car was locked, this current drop to about 15mA, which is a very little drain.

This means if the car is unlocked for a long time, it will drain the battery faster.

OBDII Headlight Initializer Dongle

Recently I got a request through my Request and Wishlist forum page about making a simple dongle for initiating auto-leveling headlights. Why would you need this? According to Mazda Workshop manual:

  • Perform headlight auto leveling system initialization if any of the following services is performed:
    • Auto leveling control module/AFS control module replacement
    • Auto leveling sensor replacement or removal/installation
    • Any service which changes vehicle height, such as suspension replacement or removal/installation

Technically you can do this with simple wire jumper, as suggested in that manual:

  • Perform Steps 4 and 5 within 30 s.

1. Empty the vehicle except for the jack and vehicle tools.

2. Adjust the tire pressure to the specification.

3. Move the vehicle to level ground.

4. Switch the ignition ON (engine off or on).

5. Using a jumper wire, connect DLC-2 terminals B and J (ground) three times at 0.5—1.5 s intervals as shown in the figure. (If the terminals are mistakenly connected, vehicle damage or fire could occur. When connecting with the jumper wire, thoroughly verify what terminals are being connected to prevent a miss-connection.)

  • The initialization is completed if the LED headlight warning light flashes three times every 0.25 s and turns off. Go to the next step.
  • If the LED headlight warning light flashes at 0.25 s intervals, the procedure may have been performed incorrectly. Repeat the procedure from Step 4.

6. Verify the LED headlight warning light.

To make this process less stressful, I added little electronics for OBDII connector, which produced 3 stable pulses after a single click on the button.

This dongle is available for ordering here