How to disconnect most electrical connectors


Mark Booth put together a helpful explanation for someone wanting to know how to disconnect the locking wiring connector underneath their seat, and I thought I would repeat an edited version of it here to help others in general.  These locking connectors are not unique to vehicles produced by Mazda, but rather are currently typical within the automotive industry.

  • Pull lock (#1; usually a contrasting color like white or yellow) partially out (should notice a detent*)
  • Depress tab (#2) and hold it down…
  • While pulling the connector (#3) away from it’s mating connector

BE SURE TO DISCONNECT THE NEGATIVE BATTERY CABLE FIRST and depress the brake pedal to discharge the circuits.  This will help insure that the electronic modules will recognize all connected devices upon re-connection.

*    For instance, in order to change the oil filter, a similar connector at the turbo diverter valve needs to be disconnected to get it’s harness out of the way, but if you are too aggressive with the yellow lock, it will inevitably fall into the bottom of the engine compartment, and the pan may make it very difficult to retrieve.

turbo diverter valve connector

photo courtesy of stevet

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 trunk release switch in the interior (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 that switch in MX-5s for some markets (like Canada), leaving only the interior switch to release the trunk lid.

Just in case Fiat has also chosen to exclude that switch in some markets (limited feedback indicates that Fiat includes this switch with the AKE option across all markets), 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 the vehicle is locked, both trunk release switches will be deactivated.

So just how did he accomplish this?  He made a jumper wire (≈6″ long) that connects together:

  • the yellow wire connected to the exterior switch that is plugged into terminal “2S” on the BCM
  • the Brown/Green wire connected to the interior switch that is plugged into “3U” of the same BCM.

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 enable it’s function.

However, I’m happy to report that collincn has verified that Sergey’s inverse solution ⇒ piggybacking the added interior switch to the exterior switch (as illustrated above)  will enable the interior switch to function, although only if you have the key on your person, as is required with the exterior switch, as reported in the same aforementioned thread.


Why would the Europeans not get an internal trunk release button?

Auto-closing windows

2017 Fiat 124 Spider Abarth Convertible

Fiat 124 Spider switch assembly

Desired outcomes:
Unlatch open top to close > window goes down less than an inch, rather than half-way
Latch closed top > either close windows then, or when the lock button is activated
Unlatch closed top to open > window opens all the way, rather than half-way

I noticed in this video showing how the windows are controlled while the MX-5 RF top is being opened and closed (at least outside the North America market):

  • windows (if closed) only drops less than an inch prior to both opening and closing the top
  • windows return to the fully closed position after the top is closed (as long as you keep the “Close Top” button engaged

After all, if you are caught in a rain storm, why would you want the windows to open halfway while you are closing the top?  But, that is minor in comparison to the window being left halfway down (or all the way down) while you are in the process of closing the top and exiting the car as the soft top currently behaves.  I’m sure it has something to do with U.S. laws resulting from someone getting their fingers injured while the windows were closing on their own.

It would seem that the logic we desire already exists in the module, since the desired movements already occur while the door is being opened and closed:

  • Open door with windows closed > windows go down less than an inch.
  • Close door with windows closed > windows return to the fully closed position.

That is why I’m following the progress of sergey’s (known as ssh16) “Automatic roll-up windows” project, especially when hitting the lock button while the top is closed) on either:

  • the key fob remote
  • or the door handle (with advanced keyless entry option)

The door handle lock button is my preferred lock procedure, since I turned off the walkaway automatic door lock feature and I never need to remove the remote from my pocket. Ideally though, I feel that the windows should close as soon as the top is latched into the closed position.

Ideally, no extra modules/hardware should be required; I hope instead that it just requires a addition/triggering of code or perhaps we’ll have to exchange the window switch module from another market that also has the door lock function (Europe may not), since that logic may also be programmed into the same module.

⇓  Sergey, keep in mind that even though the underlying switch in the 124 Spider (shown in top photo) is the same as the Miata’s, hopefully it is easily separated from the trim bezel so that the new part you develop may work with both vehicles 😉


Miata MX-5 switch assembly

Adding Lumbar Support

seats construction

The seats in our Spiders are relatively lightweight (around 30 pounds due mostly to the frame fabricated in steel) with no springs and foam like previous generation seats, so all of the comfort and support in both the seat bottom and seat back is attributed to the combination of the outer covering and the tight mesh fastened along both sides of the frame underneath that skin.  Other than the outer coverings, the construction is exactly the same whether they are:

  • Classica’s premium cloth seats
  • Lusso’s Italian Nappa leather seats
  • Abarth’s premium cloth, Nappa sport leather options or the Nappa leather with Alcantara suede inserts used in the Recaro seats
  • MX-5’s various assortment of seats

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Adding XM to non-Bose® Infotainment system?

Go directly to:     Accessing the TAU


A few people have inquired as to whether it is possible to add SiriusXM Satellite radio after-the-fact.  I thought XM was unique to the Bose setup, but the service manual implies that the only electronic difference is the additional Bose amplifier unit.  This might explain why those of us with the non-Bose system find a XM activation card in our glove box – because perhaps technically we have a XM radio in the car (just not the antenna).  According to Mazda’s Service Manual, it appears that the XM tuner is already contained in the Tuner & Amp Unit (TAU) that is common to both Bose® and non-Bose systems already, and if that is the case, it may simply be a matter of plugging a XM antenna module into the TAU to end up with XM capability. The actual system schematic is here.

I don’t think I would add the shark-fin antenna though, as there are more subtle versions available.

⇓  Here is one from Terk for $16 that looks like it plugs right in.  Because our cars are convertibles, locating the antenna on the dashboard or somewhere behind the seats may work just fine*.


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Finished my grille emblem install

grille emblem on car

I put out a request back in early November for a 3D print file for the grille emblem, and since none seemed to be available, Andrea from Italy produced a file for me.  After some modifications and getting certified to run the Maker Bot Replicator 2 printer at our library, I printed my own emblem and installed it onto my tow hook cover last week. After cleaning the car, I was able to take a photo of the finished product today.

If you are interested in the back story of this project, see my original post here.

Initializing the Power Windows

Go directly to:     Power Window Lock Switch


Many cars have both an auto-open and an auto-close function built into the window switch control modules, but our vehicles only have an auto-open function.  Auto-open will only behave properly if certain conditions are satisfied:

  • In order for the automatic window operations to function properly, they need to learn where the upper and lower limits are by being initialized.
  • Don’t start the car while closing the door. Either close the door all the way, then start your engine, or start your engine and then close the door.  Power within the control modules is interrupted during the start procedure.
  • If the engine is turned off, the auto-open feature will be disabled and the button will have to be held for the duration (as long as a door hasn’t been opened, you’ll have about 40 seconds to close your windows after shutting down your vehicle, before the switches are disabled).
  • Anytime the battery is disconnected for maintenance, the windows will need to initialized afterwards.
  • To fully open the window automatically, press the switch completely down (to stop the window partway, pull or press the switch in the opposite direction and then release it).

Power window system initialization procedure

04070102-lnd-002Resetting of the passenger window automatic function can be performed using either passenger window switch (master control switch in driver’s door or the window switch in the passenger’s door).

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Seat belt extenders

seat belt extender1

With limited access because of the tall center console, I found the seat belt buckle a little difficult to access, especially in the winter with a bulky coat on.   I’m sure there are quite a few Spider (and MX-5) owners that would agree with me that although the buckle is on a rigid riser, it could of been a couple of inches taller.


Well, today I received a seat belt extender from Seat Belt Extender Pros, and I am very pleased with the results.  Seeing some ‘Type B’ extenders for a much lower price, I called Seat Belt Extender Pros and inquired what type of buckles are in the 2016 Miata, and the rep told me “the front seats have always used a ‘Type S’ (7/8″ wide) seat belt tongue and buckle configuration”.  I resisted asking about the rear seats 😉

I got 10% off on a single extender ordering from their website ($17.95 @ with code PRO10), but I see that whlatimer found a much more inexpensive (less than $9) extender, made by Eloto and sold through Amazon.  I’m keeping the already purchased extender, since return postage would cancel out most of the savings 😉

The extenders are available in various lengths (3″, 5″, 7″, 8″+ 11″), but for most people, the smallest 3″ extension (actual total length is 4.7″) puts the buckle at a very convenient height.  No more stabbing the seat belt tongue blindly hoping to hear that reassuring click as it finally mates with the buckle.

seats and shoulder pad

Rather than having the added extension look so obvious when the seat is empty (see photo  ⇓   below), and since I had a pair of padded “Fiat” shoulder pads I had previously purchased on eBay for around $8 (I felt that rather than make the seat belt more comfortable on the shoulders, they did the opposite), I wrapped a shoulder pad around the extended buckle assembly, secured the velcro strip that runs the entire length of the pad, to end up with a nice finished look, as shown in the  ⇑  top photo.

seat belt extender 3 in black

seat belt extender2

Adding the CD Player

CD player

It seems there are a few 124 Spider owners that wish to rectify the omission of the CD player, and so I thought I would write a short article on the subject.  I am not considering this project for myself however.

Fiat chose to omit the CD players in our 124 Spiders in return for a deeper storage cubby, even though Mazda has continued installing them in the MX-5, at least in some regions like North America and Europe.  Apparently, the same wiring harnesses are used, so if you’ve got a Bose package, the wiring for the CD player will be there, as evidenced by the notation “CD player prep” on your options list.  I’m not familiar as to what else is included with the prep package (brackets?).  If you have the Technology package in the Classica model as I do (no Bose), I’m not sure if the CD wiring is included or not.

If you do make the decision to install a Mazda CD player, you would need to order the appropriate interior cubby compartment trim, to finish it off correctly.  The parts department should be able to inform you whether the necessary mounting brackets are provided (or required) with the CD player unit.  And of course, you would need to remove the negative battery harness prior to the installation (standard procedure for any electrical work) so that the CMU will recognize the addition of the CD player when the battery is reconnected.

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Replacing your radio antenna


If you find the FM radio performance lacking, don’t bother ordering a signal performance booster, as the OEM antenna already has an integrated powered amp.  As others have noted, you should check to insure that the antenna mast is snugly screwed into the antenna mount.  You probably shouldn’t get a ‘stubby’ antenna either, as your radio performance may suffer some more.

Ideally, a FM antenna length should always be 31 inches, and that is why you’ll notice that a wire is spiraling along the shaft of the shorter 16″ OEM antenna to replicate that.   You might not like the look, but if you are really out in the sticks, you might actually try a ‘true’ 31″ antenna.

HDIf a FM station offers HD, you’ve probably noticed that the sound quality is best when HD is displayed.  When the digital signal strength is inadequate, you should notice as the radio switches back to the regular analog signal.

The FM antenna also serves as your AM radio antenna, but your GPS Navigation antenna (behind your instrument cluster) and your XM radio antenna (sharkfin on your trunk lid) are separate.

Regarding the popular aftermarket 5″ rubber ‘stubby’ antennas, they too have a 31″ wire coiled internally around a much shorter shaft, but they will never pull in stations as well as OEM or true 31″ antennas, but if you spend most of your time near a large city, you may find the performance to be fine.  This ‘stubby’ that is also marketed for the Mustang fits very nicely on the 124 Spider, as shown ⇓.