Matrix Reverse Beep Mod

My 2003 Toyota Matrix has a reverse beep. There, I said it.

It’s pretty silly, and I have a hard time explaining it. Some people ask if the annoying beep is audible outside the car, “you know, like one of those trash trucks!” No, the shrill beep only tortures those in the car, thankfully.

I’m assuming that because the car is a 6-speed manual transmission, and that the reverse gear is right next to first, Toyota felt it an appropriate safety measure to sound an alarm when the driver put the car in reverse. I can’t stand it. So, why not disable it?!

With the help of some great internet sites and email lists (see references below for specifics), I got all the information I needed to proceed.

The first step was to remove the gauges cover. It just pulls right out.

gauge cover

The next step was to get the gauges assembly out. This was sort of tricky, but there are two large white hooks that keep the bottom part of the assembly locked in. There’s one screw on the top side. With enough patience, it can be removed without much trouble.

gauge PCBs

There’s one big connector that is connected to the gauges assembly. Disconnect that. Now, you’ll have a good view of that harness. Below is a picture of the connector and the wire that sounds the reverse beep. It’s a red with small black stripe. It’s the fifth position from the left on one side.

wire to be cut

Now, I didn’t want to simply remove the feature permanently. I wanted the ability to re-enable it in the future, especially if I sold my car. I certainly didn’t want to have to reverse the reverse beep mod! So, a switch was needed to toggle between the mod and the factory setting.

Similar to my Matrix DRL Mod, I chose an AC power cord from a PC for the cable, for its large gauge size and heavy insulating jacket. First, I snipped the red/black wire about 3 inches up from the connector. Second, I spliced the white and black wires from the AC cord to each end of that red/black wire in the harness. The green wire of my AC cord I bolted to the car’s chassis for ground.

switch/LED cable

Now, where to put this switch? Well, it just so happens that there is one spare button next to the radio. There are a series of three switches, two of which work on all US Toyota Matrix models. The top is the AC switch, the middle is the air recirculate switch, and the last one is unused.

switch assembly

I spoke to Greg at ToyotaPart.com and he sent me the following scan from a maintenance manual:

extra button

Those three switches are part of one assembly, so it’s not possible to buy an individual functional switch for that third bay. But I was undeterred.

The panel that covers the switches and radio comes off very easily. Just pull out from the bottom side first and then the top. There are four electrical cable harnesses and one mechanical cable plugged into the combined assembly. Three of them are plugged directly into the reverse side of the panel. One electrical and the mechanical cable are plugged into the switch assembly.

assembly back end

Removing the triple switch assembly was somewhat tricky. It’s got two plastic locks on top and bottom that I pried out with some slotted screwdrivers. Those A/C and recirculate switches have nifty LEDs embedded in them so that they light up when they are switched on. I love that functionality. I wanted to do the same for my switch option on the reverse beep. “On” would be beep disabled and an LED would turn on instead during reversing. “Off” would be beep restored.

As you can see below, there was really no accommodation for a switch travel below the switch cap. It’s really just a false switch cover. According to ToyotaPart.com, the European models use this bay for some option that isn’t available in US markets.

So the trick was to convert that plastic area into a real working switch with travel. I’ve circled that are below in red.

shortened swtich bay

It wouldn’t be an easy task, as there is no clearance below the cap for much travel. In the next couple photos, I’ve circled the usable areas where a switch could be added underneath the plastic cap.

switch in place

Next, I used a Dremel tool, otherwise known as God’s gift to plastic work, and carved down the cap base. I also had to shave off some plastic ribs that kept the false switch cover from traveling downward. See red circled portion below.

spare switch (cap removed)

The false switch cover has two latches on each side that keep it in place on top of the plastic base. I next selected a good switch that had a nice toggle detent, and which would fit underneath the switch housing. I found a good double pole, double throw (DPDT).

spare switch cap and switch

Underneath the housing, I drilled out a hole for my switch’s actuator, and used the Dremel to square the circle. Now you see the switch placed inside the hole.

new switch

On the top side, you can see the actuator protruding into the plastic base section. The actuator isn’t actually long enough to extend past that plastic base, so I needed to use some extra plastic to make contact between the cap and the switch actuator. I just used a cylindrical LED light pipe, cut down to size for this. Also, in the two circled hollow sections below, I placed springs from regular fountain pens to keep the switch cap up during travel.

switch in place

Next the wiring. I glued my switch into place with an industrial adhesive called E6000. I used a 330 Ohm resistor for my LED current drive (for about 35mA). I soldered both poles of my switch together for added current sharing.

switch wiring, resistor

I used heat shrink around the resistor and leads of the switch.
switch wiring, shrink tube

Last two wires.
switch wiring, final wiring

Next was the cap LED. I drilled a hole in my false switch cap (soon to be non-false!).

false switch cover drilled

Here is the LED from the reverse. I used a flat top LED to make it look sleek.

false switch cover w/ LED

Here is how it looks, nearly flush against the cap. The curvature of the cap prevented it from being perfectly flush.

false switch cover w/ LED

Here is the switch and its wiring back on the switch assembly.

switch wiring, front

Next was the wiring of the panel to the new AC cable harness I added. I used wire nuts for the connection to my AC cable.

wiring harness

Finally, here is the reverse LED in action. Toggle the switch, and the LED is inactive and the reverse beep is reactivated!

operational reverse LED

References:

Project photo gallery:

13 Comments

  1. I have to admit that I was disappointed that this wasn’t one of those things that beeped outside the car when you backed up…I was prepared to give you no end of grief over that!

    Quite the repairman…way to go MacGyver!

    Dremel tools are AWESOME. I bought mine when I decided to mod my computer case (put a window in, neon lights, neon fans, cool Punisher, Spiderman, and alien fan covers)

  2. Oh yeah, on a side note, if you ever need some mega bandwidth or file hosting space let me know. I have so much I don’t know what to do with it all.

  3. V. well done – my old man was fitting out our Ford C-Mac with the very same tools yesterday. Crazy world!

    btw. Those catagory images- I’m stealing those. Great idea / hack. You should post a quick how-to on the Flickr discussions… they are quite discussion-less at the moment, but there you go!

  4. You wanna come fix my dishwasher? :o(

    • Only if I’m allowed to put cool multi-colored LEDs on it. :-)

    • You could fix my washer while you’re at it. Very cool pictures! You could put that in your “Why I would make a good husband” portfolio. :lol: Any man who can tear apart the car and put it back together properly is quite a find.

      The car does still run properly, doesn’t it?

      • Hehe, yep it still runs, Mary! Ok, so maybe I need to take 2 weeks vacation to KC to make a washing machine repair run.

        Actually, I doubt I’d be much help with the appliances. Those things are way too complex these days!

  5. When nerds document…

    Seriously, when you head up here this month don’t forget your nerd equipment so you can fix the power connector on Dad’s laptop.

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