Can I pair a 3 button remote to my car which has a 4 button?

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: NC1 2.0 2007
  2. I’m based near: __Herts
  3. I’m looking for technical help or recommendations on: keyfob programming

I’ve recently bought a NC1 with only one key. I bought a second hand key from ebay and a blank key, had that cut and put into the second hand key, programmed it using ForScan and all works fine

However the remote doesn’t work at all, I’ve put a new battery in it (The red led flashes when you press a key) and I’ve done the pairing routine of ignition on/off three times, door close and open 3 times multiple times but cannot get it to work

So the question is is a 3 button key useable on a car that came with a 4 button fob ?

If so, does it need to be enabled or configured in some way ?

Is there any way of telling whether the keyfob is transmitting anything ? (without specialist equipment)

If anyone has ideas I’d be really grateful to hear them. It’s only a spare key so doesn’t really matter but would be nice to get it working

3

If it doesn’t pair using the procedure that you’ve tried it probably won’t work. Keys are fickle things with that regard.

4

There are two types of pairing you need to do with keys.

  1. Pair the chip in the key with Forscan like you have already done.

  2. Pair the keyfob to the locking system.
    https://www.youtube.com/watch?v=z7V3FH_uB6U

There are two types of key for the mk3 - you need the matching type for the above to work
One is the Mitsubishi key - identified by the mitsubishi symbol on the circuit board.
The other I believe is Siemens.

Have a look at your working key and see if it had any manufacturer ID
Then see if the second key is the same make

EDIT - Siemens key on left ( with tick ) - Mitsubishi key on right ( with no entry sign )

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5

Thanks, I’ll have a look. Tbh if I’ve got the wrong manufacturer I’m not really bothered as it’s only a spare key.

But thanks for the quick response :blush:

6

If you do have the wrong fob type - the correct ones are pretty cheap and you can move the blade/chip across to a new fob.

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7

Just some feedback as I’ve now resolved this

You do need to ensure that you have the correct make, the 4 button I got with the car (I only got one key) was a Mitsubishi, the 3-button I bought off ebay was a Siemens and didn’t work. I bought a 4-button one that was Mitsubishi and it worked perfectly, just had to sync the remote with the usual sequence of turning ignition on and off and opening and closing the door (I can’t remember the exact sequence but is easily google-able)

So whether a 3-button Mitsubishi (if such a thing exists) would work I dont know but there are loads for sale on ebay so not difficult to get hold of the right one.

The immobiliser programming is a different thing entirely (easy to do with Forscan) but if you just swap over the fob half of the key then you don’t need to worry about that

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