Hide Your Dash Cam Power Unit Inside the Mirror: Lexus GS F

A dash cam install gets judged on what you can still see afterward. A camera up by the mirror does not look finished if a module sits on the glass and a cable traces the headliner. On this 2016 Lexus GS F we put the power unit inside the mirror housing itself, so from the driver seat there is nothing to notice.

 

The other half of this job is the order you do it in. We wired the power side before the owner had picked a dash cam. That sounds backwards, and it is the most useful idea here. Once switched power is live behind the mirror, choosing a camera, mounting it, and replacing it two years later are all five minute jobs with no trim tool involved.

 

For the product overview, the fuse box argument, and Toyota and Lexus fitment, read our dash cam adapter overview and fitment guide first. This post picks up after that and covers where the module goes and when to do the work.

 

 

Wire the Power Side Before You Buy the Camera

Most people do this in the opposite order. They buy a camera, open the box, and only then find out what powering it involves. By then the camera has already decided the cable type and the mounting position.

Turn it around. The Beat-Sonic DCU-T101 dash cam power unit takes power the car already routes to the auto dimming rearview mirror, so the supply ends up inches from where any dash cam mounts. It does not care which camera you pick. Do it first and the camera decision stops being an install decision.

The kit is the power module, the plug and play harness, and three output cables covering USB-C, micro USB, and mini USB. That range is what decouples the two halves. You are not committing to a brand or a price bracket on install day, and the camera is never married to the car. Swap it in two years and the power side stays exactly as it is, untouched behind the mirror cover.

 

Stacking a Second Retrofit on a Car That Already Had One

The GS F in this install already had a Beat-Sonic front camera interface fitted for parking. That is worth saying out loud, because the second retrofit is the one people hesitate on. The first went fine, the interior went back together, and nobody wants to open it up again.

A front camera and a dash cam do different jobs. One helps you place the nose of the car. The other records what happens while you drive. They are separate systems, and this power unit only bridges one connector behind the mirror, so nothing about the earlier front camera work gets disturbed.

For the background on why these factory tie ins stay invisible to the car, our post on OEM integration covers the thinking.

 

The Mirror Cover Comes Off in Two Stages

This is the part people get wrong, because the cover looks like one piece and it is not. There is a thin panel at the front of the plastic cover around the mirror base, and that piece comes off first. Use a thin plastic trim tool here rather than anything metal.

Work the tool along the seam and lift the small panel away. With it gone, the larger cover releases and pulls straight down. Behind it you have clear access to the factory connectors and to the empty space you are about to use as a hiding place.

 

The 10 Pin Connector Is the Only One You Touch

There is one connector you need, and it has 10 pins. Press its release tab, pull it out by the body, and set the factory plug aside.

The Beat-Sonic harness goes into that now empty socket, and the factory plug goes into the other end of the harness. Both sides lock. The factory circuit is bridged rather than interrupted, so the mirror keeps behaving exactly as it did.

 

Hiding the Module Inside the Mirror Housing

You have two places to put the module. Stick it high on the windshield in a spot you will never look at, or tuck it up inside the mirror housing you just opened, where it disappears completely.

The second option is worth the extra minute. Nothing sits on the glass, and the only thing on your windshield when you are done is the camera. The housing is already open, so you are choosing a location rather than adding a step.

 

Why the Kit Includes 3M VHB Tape

The tape in the box is 3M VHB, which is very high bond adhesive rather than ordinary double sided tape. Put a strip on the back of the module and it stays where you put it.

So settle on a position before the tape goes on. Decide first, stick second. If you are not sure yet, do what we did and leave the module loose in the housing.

 

When a Tinted Windshield Changes the Plan

On this GS F we left the module unmounted on purpose. The customer had not chosen a dash cam yet, and the windshield is tinted at the top, which changes where a module on the glass would sit. There was no reason to commit to a position that might end up in the way later.

If your car has that shaded band, the mirror housing settles the question. Inside it the tint strip does not matter, because the module is not on the glass at all.

 

The Cable Run Nobody Sees

Press the cable into the seam of the headliner with your fingertips or a thin trim tool. Zip tie or tape the connector body so it cannot swing behind the cover, then reinstall the trim in reverse order, larger cover first and the thin front panel last.

Sit in the driver seat afterward and there is nothing to see. Beat-Sonic vehicle vision products live in our camera solutions collection, and our Toyota Crown front camera guide shows what a full factory style front camera retrofit involves.

 

Frequently Asked Questions

Can the power module really fit inside the mirror housing?

Yes. Once the thin front panel and the larger cover are off, there is room behind the cover to tuck the module up out of sight. It is one of the two mounting spots we recommend, and the one that leaves nothing on the glass.

 

Does the 3M VHB tape come off later without damage?

Treat it as permanent. VHB is very high bond adhesive, not ordinary double sided tape, so it is built to stay put rather than to be repositioned. Pick your spot before you press it down. If you are not sure yet, leave the module unmounted in the housing.

 

My windshield has a tinted strip at the top. Is that a problem?

It is a reason to hide the module in the mirror housing instead of on the glass. That is why we left this GS F unmounted rather than committing to a windshield spot that might end up in the way.

 

Can I install this before I buy a dash cam?

Yes, and we would suggest it. The unit is the power source only. Do it first and the wiring is finished, so adding the camera later is a USB connection and a mount.

 

What happens when I want to swap cameras later?

Nothing behind the mirror changes. Unplug the old camera, plug the new one into the matching output cable, and mount it. The harness, module, and cable run stay as installed.

 

Does adding this on top of an existing camera interface cause a conflict?

Not on this car. The GS F already had a Beat-Sonic front camera interface fitted and the power unit went in on top of it. They are separate systems, and the power unit only bridges the factory 10 pin mirror connector, so auto dimming and the other mirror mounted features keep working. More on that in our post on whether retrofits affect cameras, sensors, or controls.

 

Want Us to Do It Instead

If you would rather not have a trim tool anywhere near your headliner, bring the car to us. We are in La Mirada, California, and a dash cam power unit fit is one of the quicker jobs on our board. Send our install team a message and we will find you a time this week.