Adding Power Folding Mirrors to the 2018 Honda Odyssey EX-L

Warning: The following describes how I successfully added power folding mirrors to a 2018 Honda Odyssey EX-L using parts from the Elite trim. I've documented this solely for my own personal use. Use this information at your own risk.

Summary:

The 2018-2019 Honda Odyssey is a tight fit through a 8' wide garage door. I needed to manually lower the driver-wide window and pull in the mirror simply to get into the garage without hitting the garage trim. Power-folding mirrors are available on the 2018 Honda Odyssey top Elite trim but cost ~$10k extra above the EX-L trim which wasn't worth it. Thus, my goal was to provide a few extra inches of clearance for minimal cost.

Goals:

Add a power folding mirror to the 2018 Honda odyssey EX-L trim

Instructions below likely apply to any trim of the 2018 or 2019 Honda Odyssey but my car is 2018 Honda Odyssey EX-L

Minimize impact on Honda-installed components and circuits

The 2018 Honda Odyssey Elite has power-folding mirrors and thus it's possible to buy the Honda-specific switch. I didn't pursue this option because after looking at the wiring diagrams it looked like the power-folding wire harnesses were connected to the power mirrors and might require proprietary programming at a dealer. Thus, I'm using a simple momentary DPDT switch which requires holding for a few seconds to extend or retract the mirror. An added benefit of this approach is that the power-folding is a separate circuit and minimizes impact on other components and their warranty.

Only driver-side mirrors

I only needed to mod my driver-side mirror to provide enough clearance to fit in my garage. It should be possible to extend this mod to also add the passenger side.

Parts:

Carling Technologies 6GM5M-78 DPDT switch ($15 at mouser)
Quick connect set ($19 from Amazon)
14 gauge primary wire in red / black ($6 x 2 from Lowes)
Small cable ties
Add-a-Circuit Fuse Holder ($8 from Amazon)
Honda parts (purchased some from Hondapartsnow.com and others from local dealer):
- 76254-THR-A32 Mirror sub-assembly L ($129)
- 76256-THR-A31 Mirror wire-harness L ($25)
- 76255-THR-A31 Mirror housing set L ($52)
- 77755-TBA-A00ZA Switch blank ($0.58 - optional - the car comes with a switch blank you could pop out and modify. I decided to purchase a couple extra because modifying the plastic switch blank to accept the DPDT switch might take more than one attempt and I felt it was worth it to have a few spare on hand given their price)

Total: $260

Tools:

10mm socket (to remove mirror from door)
8" socket extender (10mm bolts are deep within door)
Torx screwdriver to remove mirror actuator from housing
1/2 spade drill bit
Diagonal cutting pliers
Pliers
Wire crimper ($14 from Amazon)

Service Manuals:

Steps:

Select a switch

Given the blank on the left, driver's dashboard needed to find a switch that was small enough to fit through the rear while being large enough to handle the current. After much searching a momentary DPDT switch from Carling Technologies 6GM5M-78 was chosen. This switch has 1/4" quick connect tabs.

Hollow out the switch blank to accept the Switch

You can remove and use the existing switch blank but I ordered a few extra just in case I needed to experiment. Using a diagonal cutting pliers and pliers I hollowed out the inside support plastic tabs, cutting off the back locking tabs and slimming some of the side positional tabs. At the end of the day the DPDT switch is going to get screwed onto the switch blank and the whole part jammed back into the dashboard panel which fits snuggly and holds everything in place.

I marked the center of the front of the switch blank and used a 1/2" spade drill bit to cut a hole to insert the switch.

After a few rounds of cutting and re-checking fit the 1/2" bushing from the SPDP switch fit through enough to allow me to place the locking nut on the other side, securing the switch to the switch blank.

Add cross wires to switch

The DPDT is wired to reverse polarity. For background see instructables HOW TO: Wire a DPDT Rocker Switch for Reversing Polarity

DPDT corner - DPTP opposite corner - battery (red wire)
DPDT corner - DPDT opposite corner - ground (black wire)
DPDT middle - will be wired to mirror in a later step

Add battery connection

Using an Add-a-Circuit fuse tap and a 20 AMP fuse I tapped into the fuse box. I selected another 20A fuse for simplicity, using the "right power window" fuse. This battery connection will be crimped to to the red "cross wire" as described above.

Add ground connection

Remove the drivers side kickplate. To do this, loosen the bottom door sill enough to remove the side moulding enough to loosen the kickplate. There are two tabs you need to pry out and then while pulling the hood release latch horizontal, slide the kickplate out of the way.

On the metal vehicle body is a grounding nut, seen in the very top of this photo after the kick plate has been removed. Loosen the nut and attach the black "cross wire" as described above. For the connection I used a ring connector which I cut off part to make it U shaped, though it's possible to remove the screw completely and perhaps thread it on.

Remove drivers door panel

With driver window down, remove two cover panels to reveal 3 screws. Two screws are behind the door open/close lever and the third is under the armrest area. With the three screws removed, beginning at the bottom pry the door panel off and eventually lift up and out near where it reaches the window. Holding the panel, release two wire harness connectors and slide the panel forward to slide the locking mechanism out of the door. More details in video.

Fish wire from under dash to near mirror connector

This is probably the most difficult step as it requires fishing two cables in tight spaces from under the dashboard, out into the inside of the door, and then out to the front of the door before terminating near the mirror wiring harness.

Remove both sides of the black wire loom (black rubber connect which protects wires from the elements) on the door and car side. This might not be entirely necessary but helps get the cable through.

Remove the front water shield from the driver-side door. There's an outline of sticky / spray foam that you can pry off with your fingers.

Starting inside the door, poke a 14 gauge wire through the wire loom opening and through, pulling out near the driver side kickplate. This is not easy and took awhile. Once one wire is through, use it as a pull wire to pull through the second wire by duct taping the end.

With the end of a wire sticking out the door, thread it through the pear-shaped black rubber gasket inside the door frame so it comes out near the exposed part of the door with the rest of the wires. Once one wire is through, use it to pull the second wire by duct taping the end of the second. Once both wires are through, pull them so the wire is appropriately the same length as the wire harness that's already inside the door. Use some duct tape to tape the two new wires to the existing wire bundle.

If the black wire loom was disconnected from either door or car side, reconnect by finagling it back on. I needed a helper to apply pressure to push the white plastic cable connector from inside out towards the door so I could get the black rubber wire loom back on.

Before / after pictures of inside the door:

Remove the mirror

Disconnect the mirror wire harness connector.

Remove two black circle disks and push out the mirror harness gasket circle. Behind the three openings are three 10mm screws. Using a 10mm socket plus extender, carefully remove the nuts and avoid letting them drop inside the door. Make sure someone is holding the mirror before the final nut is removed.

Pull the mirror connector out.

Modify the mirror wire harness

The mirror wire harness purchased for this project will be modified to instead of plugging into an Elite-trim door wire harness it will instead connect to the two red / black wires fished from behind the dashboard.

Remove or cut-out two wires from the "elite" mirror writing harness connector:

Orange

Orange/black

These can be removed by using a tiny flathead screwdriver and inserting it through the front (connection side) while gently pulling the wire from the rear (wire side).

Once the two wires are removed, strip and crimp them to two blue circle male connectors from the quick connect kit.

Run the elite mirror wiring harness through Elite mirror sub-assembly. All the connectors need to go through the small circulator opening (note that the Elite sub-assembly opening smaller than non-elite as shown in pictures) and not based on cable length. The circular turn signal is the biggest so that needs to be pushed through first, followed by the long/narrow mirror position adjustment connector, followed by the remaining connectors.

Upgrade the mirror

Remove the actual mirror / mirror holder by carefully pushing mirror in the upper right to create enough space to insert a flathead screwdriver into the lower left of the mirror. Once the flathead is inserted, rotate 90 degrees to create a gap and then insert another flathead screwdriver to do the same further along to expand the gap. Eventually the mirror can be carefully removed.

Cut out side towards the two openings. Keep prying until you get the existing mirror housing off. It may be possible to separate the mirror housing without destroying the EX-L part but I wasn't able to figure it out and I didn't need the EX-L part after performing the upgrade. At this point there's no turning back. :)

Attach the colored skull cap to the new Elite housing. The existing turn-signal should remain on the colored skull cap. Plug the circular turn-signal connector to housing.

Insert the mirror sub-assembly to the skull-cap and attach with screws.

Insert the mirror positioning part with screws. Attach connectors.

Attach the power retract actuator connector and insert connector into holder.

Attach bottom of housing to mirror base with two screws. You may need to rotate the mirror to gain access to the screw holes.

Insert top of housing.

Reinstall the mirror

Follow "Remove the mirror" in reverse.

Push the black circles back in place. The existing adhesive seemed to be sufficient for it to stick.

Push the mirror wire harness gasket into place.

Connect the mirror

From the two (red / black) wires coming out of the door gasket, cut to length and strip and crimp blue female connectors. Use some zip ties to attach the wires to the existing wire bundle.

Connect the wires to the switch

Under the dashboard, find the two wires (red / black) and crimp a 1/4" female quick connect to each. Attach these to the inside / middle pins of the DPDT switch.

Here's what the complete wiring of everything looks like:

Check that everything works

At rest the momentary DPDT switch is in the middle. Holding it up or down for a few seconds results in the power-folding mirror retracting or extending. I made it retract when toggled up and extend when toggled down. If this is reversed then simply flip the two middle DPDT switch connectors so ground and power are reversed.

Questions:

The original mirrors in the EX-L are textured black and non-glossy but the Elite mirror housing is glossy black - why?: I'm not exactly sure. Maybe all Elite trim have glossy black trim? Maybe replacement parts ordered from Honda aren't exactly the same as what's installed in the factory. Regardless, the part fits and they're both black.
What would you do differently next time?: Although I haven't heard any rattles, I'd consider applying some fuzzy / soft duck tape to the wires inside the door as needed. Seems some of the other visible Honda wire harnesses use this material.