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RX-7 2nd Gen Specific (1986-92) RX-7 1986-92 Discussion including performance modifications and technical support sections.

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Old 11-07-2019, 05:20 AM   #1
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Default Alternative to pricey driver's power window switch - FD3S power window switch???

So my stock OEM FC3S driver's side power window switch cluster died - specifically, the driver's side window did not want to go down.
It was giving me hints for the past several months by just hesitating for a split second before going down eventually.
A few weeks ago, it stopped going down totally.

This switch is a Mazda OEM part that replaced the original set of switches about 20 years ago with about 50k miles on it.
(Yes, the car got very little use for the past 20 years.)

Taking the switch apart, the contacts were burnt and eroded from the high current passing through it - the switch directly controls the power window motors.
There are write-ups for relay retrofits to keep the current down and maximize the life of your power window switch, but that's for another write-up.

I was now looking for a replacement...
Prices for a Mazda OEM direct part starts at about $150 - $160 and go up.
At the same time, I saw a lot of cheaper *FD3S* power window switches on eBay from $35 - $50!
More research shows that these were Made-In-China knock-off's - thus the cheap prices.

I took a chance...
The plugs looked the same, but the FD3S unit had one less pin / wire.
I didn't research the wiring diagrams, but I needed something NOW.
When I got the switch, and checked out the wiring diagrams...
Basically, the only difference is that the FC3S unit ON / OFF switch interrupts +12VDC side of the circuit, while the FD3S unit interrupts the GROUND side.

If you do this conversion, it is very difficult to get the ON / OFF switch to work correctly, since the circuitry is on the circuit board.
The easy option is just to wire the FD3S switch to be fully ON all the time, and the ON / OFF switch does not do anything.

I cut the plug and most of the wires off the (dead) FC3S power window switch; I cut the plug off the new FD3S power window switch.
The rest of the wires were just +12VDC, ground, driver UP, driver DOWN, passenger UP, passenger DOWN.
I spliced the FC3S ON / OFF switch wire into the +12VDC wire and called it a day.

My switch had AUTO down for both driver's and passenger side windows - over the stock OEM FC3S unit.

One cavaet - my FD3S power window switch had thinner wires on it - I dunno how long this cheap switch will last.
I really recommend doing the relay retrofit, as mentioned above to give you best life.
I'll be doing a full write-up on that - hopefully - shortly.

Surprisingly, the switched dropped right into the stock FC3S driver's power window switch location...

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Originally Posted by TitaniumTT View Post
because you're only as good as your backup
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Old 11-14-2019, 07:35 PM   #2
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That's a great find, I'm surprised the FD switch drops right in the FC driver's door panel as nicely as it does! I wonder if the FD passenger side switch would fit in the FC passenger door as well? Being a bit too OCD, having switches that don't match would make me nuts

I did the relay mod on mine, and it definitely helps with window operation and once done, the switches will last forever. Instead of doing the individual relays, I found a how-to write-up on the other forum that essentially accomplishes the same thing with a pair of DEI 451m's. Here's a link:


The 451m's are basically a pair of high-current, sealed automotive relays in a single inexpensive package. With those, it's a simple job to add them to your existing PW wiring (one 451m for each door/PW motor). Between the relay/451m mod, and cleaning/re-lubing the PW regulators, it's like a new car - windows zoom up & down with zero drama.
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Old 12-26-2019, 08:27 PM   #3
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With me needing to replace my switch, this would be a good time to install fd switches. Awesome info!
leaving my carbon footprint....one start up at a time
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