Hi guys, i have a some problem. I have to much voltage on my battery. There was 15.10 V and already my ABS was fried and 100 amp also. I changed my battery, alternator, fried ABS pump, 100 amp and still i have no idea whats going on. Maybe is earth/grounding problem? But Wires looks okey for me. Maybe somebody have similar problem or maybe somebody have a good advice what can i do. I have Mazda from 2003.
- My model of MX-5 is: NB
- I’m based near: Gloucester
- I’m looking for technical help or recommendations on: electrical problem
My immediate response is that the voltage regulator has failed. If it’s actually passing huge current it’s not a connection problem. I guess it’s blown the 100A fuse.
Not sure where the regulator is on an NB. It could be built into the alternator or on some models it’s a function controlled by the ECU.
JS
Hi
If I remember correctly the voltage is regulated by the ECU on the MK2.
It may be worth checking the ECU located in the passenger footwell, as it may have suffered from water damage at some time.
If you are lucky it may be corroded wires, if not it may be a fried ECU.
Good Luck.
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If i good remember voltage regulator its in alternator but alternator is new so i dont think so and yeah i need to check ECU because it can be that problem but thank you for your repsonse 
And i forget to add - i have battery light on my dashboard but i think its doesnt matter on this way.
‘New’ alternator or not this is all shouting faulty alternator to me…
JS
For me also and i understand but before when i changed the old one they test it and it was okey but anyway i changed for new one and there is the same problem…
Alternator is regulated by the PCM on NB.
So now I’m pretty sure it can be a ecu problem. I’m gonna take this out today and maybe send ecu to test it. Thank you guys for your help.
Beat me to it! I was unfortunately using ‘faulty Alternator’ as a catch-all covering the generator and the regulator. Sorry.
JS
The voltage regulator is physically part of the alternator on all MX5 cars 1989 - 2005, MK1 - MK2.5 and probably subsequent models; MK3 & MK4.
Difference with the MK2/MK2.5(1998-2005) compared to MK1/Eunos(1989-1997ish) is that the MK2/MK2.5 ecu controls that regulator.
One of the first issues with water ingress into the passenger footwell and associated ecu damage is the alternator regulator controller on the ecu. Usually, from my experience, water damage to that component stops it dead, so no charging on alternator at all. Perhaps overcharging is another characteristic or maybe there has been another problem; perhaps an electrical spike(egr or similar) or simply component failure.
15.1 volts is too much as usual expected is around 14.5 volts. The result of this mildly excessive charging voltage is a marginally overcharged battery and associated gas production and shortened life. The other problems you have would not be caused by a charge rate of 15.1 volts in my opinion.
I tried to take out my ECU today but there is a 2 very unusual bolts and i need bolt remover or something like this but of course i had some water and its dump. Before when i had this problem i have been in garage and they changed only spark plugs, oil filter, fuel filter and exhaust because i had a lot of whole in the old one. Today i checked i have 14.80V. I have been in 2 garage and they have no idea whats going on. This is a good idea to test ECU?
Hi guys, i had some time and I took out my ecu and that what I found. Maybe this is a problem with high voltage?
Certainly doesn’t look right!!!
Right?! 
I’m happy because I found something and the 3 other garage didn’t. I already spoke with one guy and he will fix this for me. I hope that is a problem.
