Hi, I bought my mk3 2008 last week and it had been brilliant fun. However, today the alarm went off for no reason this afternoon…and kept going for hours (I wasn’t home but my neighbours told me, they love me right now). When I got home I tried the key fob, turning on the ignition and starting the engine, none of which stopped the alarm. I had to disconnect the battery to stop it. I’m thinking it must be an after market alarm or else why wouldn’t it stop when I started the engine? That said, it is a standard key fob I have. Anyone got any ideas why it wouldn’t stop when I zapped the car and started it?
A well known hiccup that causes alarm activation in Mk 3’s is if a phone is left in the car but I would have thought that it would switch off when the ignition was switched on ( not sure about that last bit).
Yep, been there, done that, most embarassingly when the examiner approached the car to do an MOT.
You would expect the alarm to stop when you started the car (also tried manually locking / unlocking etc) but mine didn’t either. As you say, disconnect / reconnect the battery stopped it . . . for a while.
You don’t mention the ABS & DSC lights coming on after the battery disconnect so I assume you know how to clear them.
In the end it was down to the bonnet microswitch being just on the edge of operation so triggering intermittently. There’s a few similar threads on here about that causing intermittent alarm triggering.
From memory, the microswitch itself is operated by the sprung sliding plate which locks the bonnet and in my case judicious bending of the microswitch lever arm cured the problem.
Oh wow, you are describing it perfectly. And yes the dsc light has come on, do you know how to clear it. Thanks so much for advice, this is exactly why I joined the club and hoped to hear from nice helpful fellow owners. Thanks Buddy
The clear the DSC light, turn on the ignition, move the steering wheel to full lock left and right, turn off, turn back on and the light will have gone.
Super, will try it tomorrow. Thanks
There’s a wealth of information on this forum and with the spread of experience you’ll probably find the answers to just about any problem with any model. As a new Mk3 / NC owner you’ll want to read the threads on scuttle grommets and clearing the rear drainholes to prevent potential water ingress problems, and slow recoil on seat belts if that affects you.
Above all, enjoy your MX-5 in this glorious weather 
. . . And raising the bite point of the clutch if you find that it’s only fully disengaged at carpet level.
Great tips, thank you. The steering wheel procedure removed the warning light, I’ve removed a blue tooth device from in the car and just ordered a trombone cleaner to clear out the drainage holes!
That doesn’t work for the nc mate. There’s a YouTube video by the mx5 restorer how to clean the drainage holes. If you stick that in the holes you will get it stuck
Didn’t know about the lock to lock on steering to clear the warning lights after a battery disconnect. I always just ignored them as they go away after driving about 20 metres… might be because I have to steer in that 20 metres.
Worked fine for myself and several others on here, as long as you feed it in from the top.
My trombone cleaner had brushes at both ends. I cut one off and fed this flexible wire end down through the elusive drain holes and pulled it from the bottom once the wire end came through.
fair enough. never tried shoving anything in there myself cuz I saw this guide and the connector that goes into the hose has some protrusions that may get the thing stuck. so I only had them cleaned once a year
It’s a pain finding the holes, oh yes!
Done mine several times on NC with no problems.
Always send the cleaner through from top to bottom and never pull it back to the top.
Never got it stuck…yet…