Adding Paddle Shifters to Classica / Lusso

[UPDATED 5/28/2019 with BBadger’s most recent results and photos + 1/9/2022 with Brendan J’s feedback and photos]

I happened to see an interesting thread on the 124Spider forum that BBadger brought up, having to do with adding paddle shifters for those of us not owning the Abarth 124.  I’ve already written about adding Sport mode (and it is looking promising), and now, the more I study the MX-5 Service Manual, adding paddle shifters looks equally promising, by simply ordering the parts from your Mopar parts source.  Keep in mind though, that because the paddles are common across several Mazda models, they may be much easier (and cheaper; around $50) to obtain quickly through Mazda parts distributors, by ordering Mazda part numbers:

• N243663P0 for the paddles and wiring
• N24532750 for the set of (4) screws
• N2453204902 for the respective rear cover

Although the Info and Cruise Control switches are wired to the Start Stop module, apparently, the paddle shift wiring is missing from those same harnesses:

1. From the paddle harness to the clock spring (3K (for ⇓), 3G (for ⇑) and 3I for ground), and needs to be added.   See section First Missing Wiring Segment
2. In addition, the paddle shift wiring is also missing from within the clock spring feeding the Start Stop unit 1N (for ⇓) and 1L (for ⇑) and bypass wiring from steering wheel clock spring (1D (for ⇓) and 1H (for ⇑) needs to be added, and this is done by modifying what Mazda calls “SHORT CORD” (Part # N256-67-SH0), one of 2 short harnesses that are taped together, connecting the clock spring to the front wiring harness behind, and from there to the Start Stop unit.  The ground circuit (1F) should already be in place.  Per BBadger, the tape wrapping the two harnesses needs to be cut, so that the short cord can be unplugged at both ends for removal and modification.   See section Second Missing Wiring Segment
   

diagrams are courtesy of Mazda; click to enlarge

note the 3 empty terminal slots for the paddle shifter circuit

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First Missing Wiring Segment

The first segment of missing wiring is the paddle shifter harness (shown as the green offshoot harness in the CX-5 photo below) will have to be addressed by one of the following options:

• wire the paddles to the 3 empty slots in the clockspring connector yourself (up, down and a shared ground)
• borrow the green offshoot from an upgraded steering wheel harness (Mazda # BNK8664M2) for the upgraded steering wheel wiring that plugs into the clock spring connector, to end up with the connector that the paddle shifter switches plug into (circled in red)
• remove the steering wheel switch pods and replace the entire steering wheel wiring harness with the new upgraded harness, which will then include the connector that the paddle shifter switches plug into (circled in red; if you choose this option, be sure to order the correct harness, ie. adaptive cruise requires yet a different part #)

⇓ Brendan J took this project on in December 2021, and chose to go with option #3 in his 2020 Lusso, stating:

I had to re-wire by hand the whole harness for the steering wheel controls.

I would have preferred to connect everything using butt connectors so that it would be easy to remedy incorrect connections, but since space is at a premium inside the steering wheel and I don’t have a soldering iron, I had to twist and heat shrink the wires together – securing it all with electrical tape to make sure everything stays in place.

[ameridan added ➤ I don’t recommend skipping soldering when you can buy a soldering iron at Walmart for under $6, or use heat shrink connectors that have the solder built-in.]

Also, when removing the plastic trim on the steering wheel once you’ve got everything the horn/airbag assembly off, remove the black plastic rear cover FIRST. This exposes the back of the steering wheel where you can use a flat head screw driver to push the chrome trim/steering wheel control pods out and off of the steering wheel.

The black plastic rear cover is made of a very durable plastic, it is not likely to break. However, the plastic for the chrome pieces and the control pods is VERY BRITTLE, I broke 4 clips trying to figure out the most optimal procedure.

Finally, note the 14-pin-connector comparison I made in Photoshop. This may seem intuitive for some folks, but it took me some trial and error to figure out how to connect the new harness to everything. The new harness has the same 14-pin-connector as the OEM, thankfully, but unfortunately the OEM harness is hard wired/soldered to the steering wheel control pod circuit boards, making a simple “plug and play” solution impossible.

photo courtesy of Brendan J

Using the “diagram” above, it should be very easy, if not straight forward, to connect the new harness to the steering wheel control pods.

The only other issues I ran into were during the second half of the install, but those had more to do with the fact that there’s not a whole lot of space to work with under the driver-side dashboard and I’m not a small person to begin with.

photo courtesy of Brendan J

Thank you for the additional info Brendan.

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Second Missing Wiring Segment

The second segment of missing wiring is to the Start Stop unit from within the clock spring, and will have to be addressed by doing the following, per BBadger (he has a Classica, and although there is a small chance that the Lusso wiring may include this circuitry, at this point, we really doubt it):

The existing Short Cord (C-18) has all the wires. There must be a disconnect somewhere in the Start / Stop unit from the clock spring connector. You need to bypass this using the 3 pin wiring harness from Japan Parts (part # 479-006-003) (see IMG.3196__).  They send out two versions, one with long pins and one with shorter pins. Use the longer pin one.

One end with the three pins goes into the three empty pin slots in the clock spring connector under the steering wheel (remove shroud to access) next to the yellow connector that connects to the airbag (IMG.3156__ and IMG.3205__ with green, black, and yellow inserted.) You will need to open the connector lock in order to insert the pins easily (IMG.3150__ shows this same connector unlocked under the airbag – easier to see here, note that the center section is raised (unlocked) slightly by about 1mm. You will need a small flat head screwdriver or pick to open. It runs across the middle of the connector on the bottom , pry up from each side. Reconnect this after you have the three wires installed and locked back down.

On the other end of the Japan Parts wiring harness, you connect a ring connector to the black wire. You will need to add in some extra wire to make it longer, I just used the red butt splice connector included with the part and 12” of extra black wire I had on hand. This gets grounded to the vehicle chassis (I drilled a hole into a bare metal area nearby and grounded it using a sheet metal screw [IMG.3248__]).

Cut off the pins on the yellow and green wires and crimp on the male T-Tap connectors.  The reason I suggest using T-Taps – they allow you to disconnect the male from the female should you cross the wires – meaning that the Up Paddle Shift actually causes a downshift and vice versa.  It is easy to correct with this type of connector just by switching the male connectors.  On the removed Short Cord extension, carefully peel back the insulation so that you can tap into the light green and blue wires associated with 1L and 1N using the female T-Tap connectors (IMG.3230__, IMG.3238__, and IMG.3239__) and rewrap. Connect the male T-Taps into the females and reconnect the Short Cord connectors back into the receptacles under the dash.

Notes:

There is no need to insert pins into the 32 pin Short Cord connector, the pins / wires are already installed, just need to tap into the wires. You can see the two wires to tap into in the pic labeled (IMG.3167__).

Hover over these images for their file name, and click on those you wish to enlarge

this photo album, courtesy of BBadger

photo courtesy of Lamikeith

[ADDED 10/21/2019, as a reflective summary of sorts]

Goaterguy asked:

BBadger, just so I’m clear and have everything I need before I start tearing things up, the parts I’ll need for this project are:
• N243663P0 for the paddles and wiring
• N24532750 for the set of (4) screws
• N2453204902 for the respective rear cover
• “SHORT CORD” (Part # N256-67-SH0)
• borrow the green offshoot from an upgraded steering wheel harness (Mazda # BNK8664M2)
• 3 pin wiring harness from Japan Parts (part # 479-006-003)

BBadger replied:

Hi Goaterguy,
Yes, your parts list is accurate.
• For N24532750 you can use 10-32 1/2″ machine screws.
• I would also recommend buying a new steering wheel nut Mazda part# 999481200 rather than reusing the removed nut again.
• I ordered the “Short Cord” just to have on hand as insurance in case I damaged the original one when tapping into it or if I ever needed to remove the paddle shifts for re-sale of vehicle. Your call on that part.
• An automotive pin removal tool may also come in handy to scavenge the green offshoot from BNK8664M2. I was able to get the pins to release from the connector using a flattened out staple gun staple, but it would have been easier with the right tool.

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Clock Spring

I found these videos to be educational regarding the clock spring, which contains a ribbon cable inside, rather than slip rings, which was the assumption I had made.  There is a steering angle sensor that needs to be kept in mind, as everything goes back together, as well.  Although it would seem logical that the clock spring units would be common for all MX-5 and 124 Spider variants, that turns out not to be the case, as BBadger found out.

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Santtu has a manual shift Lusso, and had the idea to add paddle shifters, so that they could each trigger a cruise-control function as an alternative to the non-intuitive dedicated steering wheel switches.  Seems like connecting the paddle switches so they tie into 1Y and 1Z on the Start Stop Unit, rather than 1L and 1N would do the trick, but it turns out to be impractical, since body ground isn’t involved, and you would have to introduce the correct resistor values as well.  Otherwise, all the paddle switches would do is Cancel / Turn off the Cruise Control, rather than the desired Resume / + / Set / – functions.

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Direct mode

When the steering shift switch is operated while driving with the selector lever in the D position, the gear position may temporarily switch. While in the direct mode, D and M illuminate in the indicator light and the operating gear position is displayed. The direct mode is canceled under the following conditions:

• Specified time has elapsed while driving at constant speed
• Vehicle stopped or driving at low speed
• Up switch for steering shift switch is pulled for certain period of time or more

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Disclaimer: Because of the airbag in the steering wheel and the amount of modification involved, it might be best to have these parts installed by a competent technician using  Mazda’s procedure and this article as a guide, if you are unsure of your wiring skills.