Spare key opens car via blipper buttons but won't start car

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: _2007 NC 2.0L
  2. I’m based near: Loughborough
  3. I’m looking for technical help or recommendations on: Spare key operation

problem as subject

have 2 keys, they both used to work. I recently replaced the cases as they were both looking a bit tired. I did test both keys shortly after doing this and they both worked, so one of them seems to have gone bad.

With both keys I can;
Lock and unlock the car
Pop the boot open
Turn on the Ignition so all the dash lights come on, radio works, etc.
Only one key will start the car though.

Is there a wierd procedure for getting a key to re-program like I have had with other cars eg.

Get in car, press brake pedal 3 times , open and close door, indicate left, right, left, etc, etc

2

Sounds to me like the immobiliser chip (usually hidden away inside the key case) is either missing or faulty in the non working key

1 Like
3

Try this.

Registering Keyless Entry Transmitters NB & NC

  1. Shut all doors and remove key from the ignition switch
  2. Open driver’s side door
  3. Insert key into ignition, switch ignition on, then off then remove key. Do this 3 times.
  4. Close then open driver’s door 3 times (all doors should lock then unlock)
  5. Press unlock button twice on the transmitter (doors lock then unlock to confirm)
  6. Press unlock button twice on all other transmitters to be registered to the car (doors should lock and unlock to conform each transmitter registered)
  7. Switch ignition on to cancel set-up mode.

Hope it helps.

4

Might help, at the least it shows where the chip is.

1 Like
5

rokgod,

bingo ! thanks for your link.

I had assumed that the transponder was part of the electric pack, not so.

Key #1
this key was just a little tired looking so I transferred the original key blade part ( with Transponder chip) onto a new blipper button part and obviously transferred the PCB bit over also. Key # 1 all working.

Key #2
This had a dead battery, unfortunately the case had been damaged and a previous owner had expertly and VERY thoroughly super-glued it all back together.
To access the battery I had to partiatly destroy both parts of the key fob.
This time I transferred the blade and everythig else over, but didn’t notice the Transponder chip.
Luckily after reading the advice on this page I realised what I hadn’t done and double lucky I hadn’t thrown the damaged parts away!

Have been working away from home for a couple of weeks so had to wait to do this last night.

The transponder chip is basically the same colour plastic as the key fob and mine was well glued in to its recess.
after 30 minutes of careful surgery with pliers, snips and craft knife i managed to extract it and transfer over to new kew fob assy.
Key # 2 now working fine also.

Also what threw me is that without the transponder chip you can still, open the car and turn on the IGN, you just can’t start the engine. When I tested previously I obviously didn’t try to start the engine using both keys.
Thanks again.

4 Likes