MX5 Mk2 Immobiliser Problem

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MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Tue Feb 09, 2016 7:16 pm

I'm having a problem getting my 53-plate Mk2 started. In fact it won't start for love nor money.

It was definitely an immobiliser fault, but an auto-sparkie had sorted out that problem. Could it now be a problem with the key - that seems the next logical step in the fault finding process. If so whats the best way of checking and resolving? I'm not wanting to spend a fortune on this, so any thoughts welcome. Oh and yes, I have tried both keys and it's the same issue with both!

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Re: MX5 Mk2 Immobiliser Problem

Postby drumtochty » Tue Feb 09, 2016 8:19 pm

Sorry your message makes no sence to me.

What was the original problem just saying it would not start is too wide an issue, did the engine turn over, did the immobiliser light come on when it turned over, did it try to start and splutter or did the engine just turn over but not kick into life and exactly what did the auto electrician do and exactly what parts did he change.

Lift the passenger side carpet that does not mean feel the top of the passenger side carpet. When you lift it you will see a box on the front firewall, that is the ECU with lots of wires going to it, is it damp or is there rust marks on the ecu.

This can be caused by blocked cabin drains letting water on to the ECU.

The ECU, the immobiliser and the ignition keys and steering lock are a matched set unless these are talking to each other the car is goosed.

In that case it is either a trip to the Mazda dealer to get the keys coded again or all four items need replaced.

With regards to cost, I'm afraid "I'm not wanting to spend a fortune on this" is a bit out of your control.
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Re: MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Tue Feb 09, 2016 8:44 pm

Thanks for trying to help. Appreciate you taking the time.

The original problem was that the car tried to turnover but never fired into life. I tried loads of options including checking out the ECU for dampness, but it definitely wasn't that. A blink/flash code on the dash indicated it could be the immobiliser, so I got the auto-sparkie to have a look. Didn't mean much to me but he replaced something for £30 under the steering wheel which helped it work again perfectly. After a few weeks it stopped working again. From memory the red immobiliser light should go on on the dash when the key is turned, then go off when you fire it up and the car starts. Now when I try the immobiliser light doesn't go on when the key is turned, which is why I wondered if the key is the problem. In layman's terms it looks like the car doesn't recognise the key for some reason.

You'll gather I'm not hot on car electrics, etc. so any advice is helpful just now.
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Re: MX5 Mk2 Immobiliser Problem

Postby drumtochty » Tue Feb 09, 2016 9:36 pm

Therefore now does it turn over but not start or does the starter not work.
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Re: MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Tue Feb 09, 2016 10:01 pm

It turns over fine, but steadfastly refuses to kick into life. It's not a starter problem.
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Re: MX5 Mk2 Immobiliser Problem

Postby gm » Tue Feb 09, 2016 10:57 pm

I think I'd be giving your auto sparks guy a call back - fixed for three weeks isn't much good really
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Re: MX5 Mk2 Immobiliser Problem

Postby drumtochty » Tue Feb 09, 2016 11:37 pm

That's my thoughts as well gm at the moment.

Maybe sticky fuel pump relay do not get the feeling of immobiliser at the moment
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Re: MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Wed Feb 10, 2016 10:12 am

Thanks folks.

To be fair it worked for a few weeks not three weeks, so I think the auto-spark did a reasonable job for me.

Interesting that neither of you think it sounds like a key issue though. I'll give this some more thought - perhaps it's time to sell as 'spare or repair'….

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Re: MX5 Mk2 Immobiliser Problem

Postby DrewN » Wed Feb 10, 2016 2:16 pm

Basics first - Do you have a spark at plugs and is there fuel being delivered?

If your auto electrician changed something under dash it might be wise to chat to him to see if he remembers what he did as immobiliser is under the dash.
If an ECU problem I found this link on how to change on Mazda Menders site -
http://www.mazdamenders.net/forum/viewtopic.php?f=128&t=2938
You would have to source a replacement ECU and immobiliser.
It might also give you some ideas on other things to check.

There are also a lot of forum threads on how to check fuel pump etc if you do a bit of digging on the web.
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Re: MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Wed Feb 10, 2016 4:27 pm

Thanks Drew, that's really helpful. I appreciate your advice.

There is petrol going to the spark plugs and the plugs themselves are fine.

I'll have a look back through the threads as you suggest to see what else I can pick up on.

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Re: MX5 Mk2 Immobiliser Problem

Postby rhino » Sat Feb 13, 2016 8:58 pm

Hi

Stumbled on to this thread a little late but as this is my main area of expertise, I hope I can add something useful to you.
Your keys have transponder chips implanted. The little ring around the ignition is a coil and picks up the transponder information that allows the immobiliser box(up under dash by drivers right knee) to communicate with the ECU.

Keys never give a problem. Your immobiliser must be connecting to your ECU as the starter motor is turning. Any problem with the key or immobiliser on a later MK2.5 car would mean that the starter motor will not turn - this is to avoid the possibility of cars being propelled onto trailers whilst in gear to facilitate theft. To check this just unplug the small plug that joins the transmitter coil to the loom. The security light on your car should come on and then go out to confirm the the handshake between immobiliser and ECU has been successful. You say it is not coming on at all? - given the starter turning this seems odd.

Unfortunately any problem with the ECU immobiliser would likely mean the replacement of all components that are coded together - ECU, immobiliser and transponders.

What, if anything shows on a diagnostic check?
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Re: MX5 Mk2 Immobiliser Problem

Postby drumtochty » Sat Feb 13, 2016 10:34 pm

Evening Rhino!

Welcome to the MX5Scotland Forum.
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Re: MX5 Mk2 Immobiliser Problem

Postby rhino » Sat Feb 13, 2016 11:21 pm

Thanks for the welcome Drum
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Re: MX5 Mk2 Immobiliser Problem

Postby tjay » Sun Feb 14, 2016 12:32 pm

Hi, 3 of my friends like me had similar problems with the starting of their cars. Local auto spark I know fixed the wiring and hey ho all cars now start no problem,
He did 2 in Dundee, then I took him Over to Fife t o fix Kenny's and then to Brechin to fix Bills too, all were mk1's.
Took him a bit to figure out the wiring on my car but after that only took a few minutes as others can vouch for.
At Kenny's left in with the cat, went in for a cuppa and before even half finished with Ian was at the door, car fixed and running no problem. !!
Message me if you want his contact number.
2007 Mk3 roadster/c/w electric hard top. Number 50 !!!
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Re: MX5 Mk2 Immobiliser Problem

Postby Chocolateandgold » Sun Feb 14, 2016 7:46 pm

tjay

Sounds promising - do you want to PM the number of your autosparks.

Cheers,
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