My model of MX-5 is: __ Mk 3.75 2.0 Sport Tech 2013
I’m based near: Bradford On Avon
I’m looking for technical help or recommendations on:
Engine immobiliser seems to have kicked in preventing engine cranking/starting.
The car was all working fine before starting.
Well, today I fitted my new boot interior lights from another thread, (yes I know ).
Checked it all out before permanent wiring up and all worked fine including the original boot light.
Well, somehow I must have blown a fuse as it didn’t work after finishing!
Because I keep my car in the garage I needed to get it outside and check the culprit (apart from me).
It started up fine but no interior lights working or any other ACC equipment.
Found the culprit a blown 15 amp “Room Fuse” number 5 in the handbook.
Replaced that and all back to normal ACC stuff, radio, lights etc all working.
Both original keys work on the remotes i.e open and closing doors and opening boot.
BUT, when I go to start the engine the immobiliser light flashes and the engine will not crank at all.
The same with both keys.
Can’t find any other fuses blown either.
Now I am very mechanically minded but this electrical starting issue has got me stumped.
Snowing and dark now…
Blow a fuse, drive it outside, stop it.
Replace a fuse and now won’t start, strange…
I have researched the said site, but can’t find any logical answers.
Any advice greatly appreciated.
Have you tried removing the fuse and trying to start it? i.e. putting back to the place when it did start. If it starts then, I’d undo the work you’ve done, refit the fuse and try it again. Everything was fine before you messed with it…
Yes, just pulled the room fuse that blew and still non start.
Disconnected the mod and non start.
Fuse back in (mod disconnected) and non start.
Yes, perhaps we shouldn’t fiddle!
I believe it doesn’t have Canbus on the NC?
Will plug it in tomorrow and see what flags up.
Will also disconnect the battery for 30 minutes or so and see……
Thanks.
You’ve said that you “can’t find any other fuses blown”. You can’t find any or there aren’t any? You’ve looked in the fuse box in the passenger footwell too haven’t you?
Indeed I have, hence why I got it out the garage.
I did have a look.
But need to check the 7.5 amp Engine Number 7 again from there.
But, I see fuse 14 20amp is a “starter” one.
Will double check in the daylight tomorrow and go through it all methodically and get back.
Thanks as always.
I’ve looked on mellens and I’m struggling to find a diagram with the room fuse at No15, although I didn’t spend too much time looking. But I did notice that the ignition switch fuse is the next fuse along from the room fuse on the diagrams I saw. Don’t suppose you nudged it.
Link to the new boot interior lights please. If they are LED’s I know you can get bizarre problems from my time on the TT forum because of interface issues with canbus.
If the NC2/3 starter system is the same as the NC1
In order for the starter to turn - the following fuses would need to be good for power to get from the battery to the starter relay and for power to get from the battery to the starter.
Well, been through every fuse and all okay.
Plugged in my OBD 2 reader, connects to the port but won’t connect to the ECU.
Disconnected battery for over an hour and a half.
Double checked it was fully charged reconnected and still the same.
No cranking and the security indicator light just rapidly flashes when trying to start.
When I started it up and drove out the garage it was a bit rough and initially thought it was because of a blown fuse.
Not so sure now that the two issues are related and perhaps just unlucky.
Spoke with Mazda chap in Bath and he initially thought it was the battery. But was unsure why it started and drove out and then wouldn’t start again.
Green Flag on route later this afternoon.
A mystery to me so far.
EDIT-
Green Flag turned up. Couldn’t fix it and believes it’s an immobiliser issue. Recommended an expert. Basically wasn’t interested as it’s a Mazda and can’t do anything.
Going to Mazda on Tuesday. They believe it’s the immobiliser aerial ((around the ignition switch) that has failed.
“They” don’t think the two issues, (boot light) are related.
No matter what, everything will need reprogramming and synced again.
Couldn’t find any automotive electronics expert willing to touch it.
Time will tell and my bank account will be the true judge!!
First time in 8 years and 10 months of ownership of any real issues, but hey ho.
Have you disconnected the LEDs that you added and tried to start the car? These are often controlled by pulse width modulation and can cause electronic noise which could effect the ECU/Immobilizer.
I have just read a thread where someone had the same issue.
His fix was :
I did manage to solve it in the most unusual way. I posted the details earlier but the short version is that as I was about to give up I thought about it like a computer network. So I figured I might disconnect the battery, put the key in, turn it on, leave the key in the ignition and hook the battery up as the key was in the ignition. I knew the car was partially recognizing the key because it would let me turn the ignition even with the key in my pocket. I knew I couldn’t have damaged the computer changing the battery. So I thought of it as bad cache memory and thought the key being in when I connected the power might dump and overwrite it.
So I did that and it worked! Both keys work just as if it nothing ever happened.
I have no idea if my explanation is even remotely close to how the systems work, but for whatever reason it did the job.
).
