Adding Paddle Shifters to the CX-7

GL-1970

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CX-7 GT, Copper Red
RF Paddle Shifters for Mazda CX-7

This post describes how to modify the CX-7 to add wireless shifting from the steering wheel.

Link to forum in CX-7 Engine, Transmission & Drivetrain

Overview:

The Mazda CX-7 has a manual shift option using shift-by-wire, where the shift lever can be used to sequentially upshift or downshift to any allowable forward gear. I wished to add shift levers (or paddles) onto the steering wheel, while still retaining the use of the shift lever at the same time.

There are two typical placement of paddle shifters, directly on the steering wheel, or on the steering column. After trying a couple of vehicles with this feature, I decided that shifters on the steering wheel was the most useful. However since the wheel turns, it makes connecting from the car to the shifters a bit difficult. I decided the easier option was to use a pair of RF transmitters and wirelessly send the signal from the steering wheel to the shift lever.

I removed the shift console (instructions can be found elsewhere on this forum) basically by removing the side trim pieces, unscrewing the shift lever, unscrewing the shift gate panel and popping it out. Youll have to unplug the 12V power outlet, and seat heater switches (if applicable).

The shift lever has two mechanical cables, one deals with locking the lever unless the brake lever is pressed with the key turned, and the other selects park, reverse, etc.

When the shift lever is in the Drive position, it can be pushed sideways into the Manual position. The dashboard light shows an M, and when pushing forwards or - the car goes to a lower gear, and pulling backwards or + the car goes to a higher gear. The current gear is also shown on the dashboard.

There is a 6-wire electrical connector for the manual shift feature. Two green wires go to a small lamp to light the shift gate. The Red wire goes to the - or downshift switch, the Blue wire goes to the + or upshift switch, the Yellow wire goes to the Drive/Manual switch, and the White wire is the Ground/Return wire. (I dont believe the White wire is actually Ground, so I did not treat it as such).


The following describes the function of the wires:

Key out or OFF, or key to first position:
Red=0V, Blue=0V, Yellow=0V

Key to ON, Shift Lever in Park, Reverse, Neutral or Drive:
Red=12V, Blue=12V, Yellow=12V

Key to ON, Shift Lever in Manual, Lever at middle position:
Red=12V, Blue=12V, Yellow=0V (current flows from yellow to white)

Key to ON, Shift Lever in Manual, Lever pushed forwards to - position:
Red=0V, Blue=12V, Yellow=0V (current flows from red to white, and yellow to white)

Key to ON, Shift Lever in Manual, Lever pulled backwards to + position:
Red=12V, Blue=0V, Yellow=0V (current flows from blue to white, and yellow to white)

Its the same if the car is running or not.
I did not attempt to see what happens if both Red and Blue are activated at the same time, I do not think the ECU would be happy.

So it seems that connecting Yellow to White will tell the car to go to Manual Mode,
and from there: connecting Red to White shifts down, and connecting Blue to White shifts up.


Next I cut the four wires: Yellow, White, Red, and Blue about four inches after they come out of the 6-wire connector, and soldered extensions of about 12 to each. To the end of this I attached a 4-wire female quick connector.

On the other end of the four cut wires (the wires that go to the shift lever) I soldered extensions and attached a 4-wire male quick connector.

When the two 4-wire female/male connectors are attached, the car functions normally.

To get 12V power, I spliced a wire onto the seat heater 12V supply that was conveniently beside the shift lever (Fat pink wire, though cant remember which one, as there are two in each seat heater switch pair) You could also use the 12V wire from the 12V Power Connector. I also spliced a wire onto the Ground on the seat heater connector (one of the Black wires), you could also use the ground from the 12V Power Connector.

Note: TEST these wires yourself using a multimeter to be sure youre using the right 12V and Ground. 12V should be only on when the key is in the ON position. The Ground should have zero resistance to any other grounded metal part of the car.

To the 12V and Ground wires, I attached a 2-wire female quick connector, and connected the other side of the 2-wire male quick connector to two 18 long wires.



I attached an ON/OFF switch to the front of the removed shift lever console, so it is below the radio/heater. It cannot easily be seen here, and its quite easy to attach to the removed panel. I wanted a switch to turn off the modifications in case of radio interference, or if someone unfamiliar is going to be using the car.
On-Off.jpg


To the ON/OFF switch, I attached another 2-wire male quick connector, and connected the 2-wire female quick connector to two more wires

Note: As there are now two pairs of 2-wire quick connectors, I modified one so it can only connect to its own pair. You may want to take some similar precaution in your connections so you will prevent attaching the wrong connectors together.

The end result should be a set of connections that only attach together in one way, and can be easily returned to stock condition (although with some extra connectors in the middle).

Connection-RF.jpg
 
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RF Transmitter/Receiver:
You can find a RF receiver with two remote transmitters at electronic stores. I got mine from a remote battery-disconnect device from the auto-supply store (I would recommend the electronic store as its likely around $20 and they may be able to help with the connections). What you need are two paired key-chain transmitters with at least two buttons each, and the receiver circuit board, which is likely about two inches by three inches in size. I found that my device had a 12V power input, and a ground wire. Two connections on the board outputted very low power 5V signals, when the remote buttons were pressed.

Remote.jpgTransmitter.jpg


On each transmitter I desoldered and removed all the buttons, and wired in a small click-button in the middle of the outside. Make sure that the upshift transmitter and downshift transmitter have their buttons wired to different signals. You dont have to remove the buttons if you can find a good way to press the buttons as they are.

Mounting the Transmitters:
There are many ways you can mount them. Drill or screw into the plastic, glue, velcro, or whatever. You could put them on the front, back or top of the wheel.
I wanted something non-marring, and strong so this is how I did mine:
Remove the rubber plugs from the back of the steering wheel. The bolts inside keep the airbag attached to the steering wheel. If you only undo one at a time, you should be fine. (if, like me, you lose a bolt inside the steering wheel, youll have to remove both, and then the airbag wires, to go fishing for the bolt. Make sure to first remove the battery cable & pump the brakes to remove residual stored power. In fact you should be removing the battery cable anyway, while doing this whole installation)


After removing one bolt, I made a Z out of flat metal with nearly 90 degree bends. On one end I drilled a large hole the bolt can go through. The bolt will attach the Z firmly to the wheel and the outside arm can be bent flat against the wheel, in the recessed cavity pointing away from the steering wheel. The metal has to be fairly thin to allow the bolt to have enough grip into its hole, as there are not many threads. Somewhere around 1/32 or less. I used metal from a hardware corner brace.

Z mount.jpg

I found some cam-buckles from the camping store that are black plastic like the steering wheel, very strong, and a transmitter could fit inside. I had to cut away a good deal of plastic to get them to fit well, and fit snugly against the steering wheel. The cam-buckle mounts get attached to the Z with small bolts.

Mount.jpg

Attach the transmitter to the cam lever. I flipped the lever upside down, and screwed on the transmitter. When the cam-lever is pressed against the cam-buckle mount, the button is clicked.

Paddle1.jpg
 
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Then attach a vertical post to use as the shift paddle.

Paddle2.jpg

I wrapped the post with soft material

Paddle3.jpg

And covered the visible portion with soft leather

Paddle4.jpg

The lever should fall in easy reach of the fingers just above 9 and 3 oclock, and doesnt interfere with the turn signal & wiper levers

Side View.jpg

Final Right Paddle.jpg

Of course, other mounting techniques may be possible.
 
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Electronic Circuit:
And now the circuit. If youre not handy with circuits, this project will be a bit of a non-starter. Perhaps you can get someone to build it for you..

The circuit allows you to use the upshift lever, and/or the upshift transmitter button at the same time. Or use the downshift lever, and/or the downshift transmitter button at the same time. It does not matter.

However, it prevents you from using the upshift lever and the downshift transmitter button simultaneously, or from using the downshift lever and the upshift transmitter button. (or both transmitter buttons at the same time)

How it does this, is by sensing when the shift lever is pushed, and blocking any signal to the other shift direction. (using the PNP transistors connected to the coils of Relay 3 and Relay 4). The PNP transistors will only allow current to flow when the Base is Low; so when the shift lever is pushed, the Base of the PNP transistor connects to White (Low) and this activates the coil of the relay of the other shift direction. When the coil activates, the relay closes (and the Normally Closed pathway becomes Open), thus preventing any possible signal from flowing in the other shift direction.

When the RF Receiver is inactive (or switched off), the car shifts as normal.

When the RF Receiver is active, and a transmitter button is pushed, the receiver sends a signal activating the NPN transistor (2N4124); and a relay (Relay 1, or Relay 2) closes to allow the car to think the shift lever has been pushed in the appropriate direction.

When the car is in Drive, (the Yellow wire is at 12V) the RF Receiver is always off, due to the PNP transistor which prevents current from flowing when its Base is High.


The Required Circuit Elements:
PNP transistor 2N4126 Qty=3
NPN transistor 2N4124 Qty=2
Resistor: 18k Qty=2, 180k Qty=2, 39k Qty=3
Relay 12V, 5A, SPDT, with 17ma / 700ohm coil (circuit board mount) Qty=4
Diode 1N4007 Qty=4
On/Off switch
4-wire female/male connectors Qty=2 pairs
2-wire female/male connectors Qty=2 pairs (ideally of different types see note in Overview section)
Circuit board
Mounting Box (there is a lot of room in the car, the box could be 6x4x8 or more)
Rubber Grommets to prevent wires from pulling out of the box


Circuit-RF2.jpg

I used a pre-lined copper circuit board.

Lined Circuit Board.jpg

If you use a similar one, you may make sense of this diagram of my circuit layout. Note: that I used 2 relays of SPDT and two of DPDT because thats all the store had. So the outer relays have one unused side. SPDT is all that is needed.

Breadboard2.jpg

The circuit is supposed to draw very little current, maybe at most 0.1A when the relays are activated and the receiver is receiving (since this is during shifting it should be very short in duration). None of the signals from the Red, Blue, or Yellow wires should be affected as they only go through relays, and the White wire is only drawing a very small current from the PNP transistors. All transistors are supposed to be either off, or saturated, so there should be very little heat produced through them. Almost all the power required is drawn by the 12V wires and outputs to Ground, which are fused through the seat heater or 12V Power fuse.

Note: if your RF receiver outputs different than 5V signals, you may need to adjust the 18k resistors to ensure the NPN transistor is fully saturated.
 
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Testing:

After building the circuit, you should test it before putting in the car.
Have a power supply of 12VDC, batteries would be OK (small cells, NOT car batteries).

Anywhere you see Ground, or White connect to the negative of the battery.
Anywhere you see 12V connect to the positive of the battery.

Red (R1) or Blue (B1) are 12V, but they short to ground, so you must connect a load. A good visual method is to connect a red LED to the positive of the battery in series with a resistor of around 1k. This would simulate R1. So when you ground R1 by pressing the shift button, the red LED would light up. Do the same for the Blue (B1).

Red (R2) can be a switch or just two wires you touch together, same for Blue (B2).

Yellow can be simulated by 12V for Drive, or Ground for Manual. Again, Yellow must be connected to a load of another LED/resistor series.

What you should see:
When Yellow is connected to ground, the LED for yellow will light up.
This should provide ~12V to the RF Receiver (if the on/off switch is on)
The RF Receiver should output a signal from each output when the transmitter buttons are pushed.

When the transmitter buttons are pushed, the corresponding R1 or B1 path should connect to ground and its LED should light up. You should hear the relay (Relay 1, or Relay 2) click when the transmitter buttons are pushed. Also Relay 3 or Relay 4 should click when the transmitter buttons are pushed.

When just the R2 or B2 paths connect to ground, you should see the R1 or B1 LEDs light up, and just the Relay 3 or Relay 4 will click (not Relay 1 or Relay 2).

It should not be possible to ever have R1 LED and B1 LED on at the same time, no matter how you press the transmitters or how you close R2 and B2.

Installation:

After testing the circuit, you can connect it into the prepared wiring connectors. I mounted the breadboard in a plastic box - about 6"x4"x8" and secured all the wires so they can't get pulled out. The box can go in the space under the shift lever console. There's enough room in there to find a good place to zip-tie it.

With the car off, turn the key to the ON position, but dont start the car. You should get 12V to the R1, B1, Yellow, and 12V wires. You should get Ground at Ground, and White should be at 0V.

Still, do not start the car. Press on the brake, and move the shift lever to Drive. The light on the dash should move to D. Pressing the transmitters should do nothing.

Move the shift lever to Manual. The light on the dash should move to M.
Do not press the transmitters, but push the shift lever up and down. It should shift from 1 to 2 and 2 to 1. You should hear relays clicking in your circuit.

If you installed an on/off switch in your circuit, switch it off, and try the transmitters, there should be no shifting.

If you installed an on/off switch in your circuit, switch it on:
Try the transmitters, the lights on the dash should shift from 1 to 2 and 2 to 1. You should hear relays clicking in your circuit.
Try shifting up and press the up transmitter, and try up and press the down transmitter.

If everything is working right, there will be no problems with shifting one direction and pressing the other button. (I do not know what would happen if your circuit is built faulty, so please test it well before getting to this stage. At best it would blow a fuse or perhaps just do nothing, but make sure you know what the circuit is doing before plugging it into your car, I do not know what the worst would be !!!!)

When everything is done, drive around a while, and see that the signal is good, no matter what youre pressing on the other controls, radio, heater, etc. Keep in mind there is always the possibility of another outside signal being received by the circuit, and shifting your car for you.
 
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Wired-in Paddle Shifters for Mazda CX-7

This post describes how to add shifting from the steering wheel with direct wiring
The previous posts #1 to #5 described how to add wireless shifting with RF transmitters


Overview:
The Mazda CX-7 has a manual shift option using shift-by-wire, where the shift lever can be used to upshift or downshift to any allowable forward gear. I wished to add shift levers (or paddles) onto the steering wheel, while still retaining the use of the shift lever at the same time.

It should be possible to modify my circuit from the previous post, to use directly connected shift levers. I do not know how they would be routed through the steering wheel, but it should be possible. Also the shift levers could be mounted stationary on the steering column, avoiding the problem entirely.

However its done, route the 4 wires two for each side, through to the shift levers. (Really only one is needed for each side as the second can simply be grounded)

All the wiring connectors can be prepared the same way.

The modified circuit would allow the shift lever to be pushed to the - position, and the steering wheel - lever pushed at the same time, but it should prevent any crossing over of the signal.

Many of the cautions in my previous post would apply here too. Test your circuit well, before installing in the car. As I have not tested this particular circuit I cannot ensure its success, though it should function identically to the RF receiver circuit in theory. The parts list would be slightly different, and the circuit layout would be different also.

Connection-Direct.jpg

Circuit-Direct2.jpg
 
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^What he said... much appreciated.

I've always planned to add the mx-6 paddle shifter wheel to my wife's CX7 and your second wiring scheme is exactly what I had planned on doing. Nice to have a little confirmation before diving in. Thanks again. :)
 
I've always planned to add the mx-6 paddle shifter wheel to my wife's CX7 and your second wiring scheme is exactly what I had planned on doing. Nice to have a little confirmation before diving in. Thanks again. :)


Go for it !
If you've already got the mx-6 wheel, you're way ahead of where I was. Getting a comfortable lever was by far the hardest part. The wiring is easily hidden, and there's sooo much space under the console that nothing has to be too precise.


I'm so used to it now - with the lever at hand, it's almost like thinking what gear you want, and it's there. Plus I'm mixing up the shifting, turning, headlights, wipers, radio and cruise a lot less than before... though sometimes I still end up getting song #4 instead of gear #4...


I do like the security of having the OEM lever still there as well. When I'm doing something especially important it gives the very definite feeling that I'm really driving, and not just playing Grand Turismo.


Good luck with your project, one step at a time.

G.
 
Nope don't have the wheel yet... looking for one on the cheap so it's been awhile. Those cars are still fairly new.

Will keep you updated.
 
im in the process of doing this. I have a rx 8 steering wheel with the paddle shifters. From what I can see in the wiring diagram on the rx8, there is only one wire that controls the up shift and the down shifts. im trying to figure out how to wire it together. any tips?
 
i.. im trying to figure out how to wire it together. any tips?

I started by looking at the gear shift lever and the wires that went in, to figure out what was going on. All of what I know is in the posts on this page. Good luck with the project!
 
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