Adding missing trunk release switches

Adding the exterior switch


click photo to enlarge

In the U.S., with the Advanced Keyless Entry (AKE) option, in addition to the interior trunk release switch (near the hood release lever), our 124 Spiders also gain another switch on the underside overhang of the trunk lid itself in-between the pair of license plate lamps and, if you have the Infotainment system, to the right of the ParkView reverse camera.  Mazda has thus far decided to exclude the camera in the MX-5, and in some markets (like Canada), that exterior trunk release switch, leaving only the interior switch to release the trunk lid.

Limited feedback I’ve received indicates that Fiat includes this switch with the AKE option across all markets, but just in case Fiat has also chosen to exclude that switch in a particular market, I’m bringing up a solution that Sergey (ssh16) has come up with as a nice alternative, and that JumperThumper has verified in his Canadian MX-5, which involves “piggybacking” the exterior switch (don’t know the Fiat part number, but the Mazda part number is N243-56-8D0) with the interior switch, as the wiring back to the Body Control Module (BCM, inconveniently located behind the left kick panel in close proximity to the interior fuse panel) should already be in place.

The piggybacked switch will actually be more convenient than the intended application, as you won’t need to have the key on your person to activate the exterior switch.  It will work whenever the interior switch is allowed to work ⇒ whenever the vehicle is unlocked.  When both doors of the vehicle are locked, both trunk release switches will be deactivated.

So just how did he accomplish this?  He made a jumper wire (≈6″ long) and with quick-splice wire connectors, he connected together:

  • the yellow wire connected to the exterior switch that is plugged into terminal “2S” on the largest BCM connector (#2 of 3)
  • the brown/green wire connected to the interior switch that is plugged into “3U” of the other (hidden) BCM connector (#3 of 3)

trunk switches

There are links to wiring diagrams and illustrations in the referenced thread.

Adding the interior switch

For those that have wiring leading to a dummy insert (as pictured below) rather than an actual interior switch (Europe and Australia market?), a few readers have already discovered that purchasing and installing an interior switch (Mazda part number GJR9-66-630A) and plugging in the harness will not, by itself, enable it’s function.

However, I’m happy to report that collincn has verified that Sergey’s solution works inversely ⇒ piggybacking the added interior switch to the exterior switch (as illustrated above)  will enable the interior switch to function, although only if the requirements allowing the exterior switch to function are met (i.e. with AKE, you’ll need the key on your person, as is required with the exterior switch).


Why do the Europeans get this blank plate rather than an internal trunk release button?


2 thoughts on “Adding missing trunk release switches

  1. I can’t comment on the other variants of the 124 Spider, but for the Canadian version of the Abarth 124 Spider, there is both the exterior switch (under the overhang on the rear deck lid), and the interior switch mounted low on the dash to the left of the driver’s left knee.

    Liked by 1 person

  2. Thanks Cal. Perhaps my article won’t be helpful for many Spider owners, but I’ll leave it be just in case. Perhaps Fiat chose to include the AKE exterior switch across the board.

    I know Fiat also added the reverse camera to the Technology package for all regions, unlike Mazda’s decision to leave it out of most MX-5s until the 2019 Model Year (starting around May of 2018).


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