1999 Miata pindicates 17 volts when running


Asked by Jan 17, 2015 at 11:37 AM about the 1999 Mazda MX-5 Miata Base

Question type: Maintenance & Repair

replaced alternator and have been to several repair places. No one can solve this problem,

3 Answers


I think the problem still might lie in your alternator. for some reason it is overcharging.

Tom Harmon

Turn your headlights on and check the voltage again ... ... If that alternator is still putting out 17 volts, you have one helleva alternator. Most alternators will give you between 700-800 watts and if that voltage has not dropped with headlights on you are hitting close to 340 watts ... without a correction you will soon start having premature failures of everything from Headlights to coil-pacs Most cars run a little over 14 VDC. ... Most alternators have a built in regulator so it gets changed when the regulator gets changed .... however, in todays world where the regulator may be a separate part # ... I would not assume anything


Tom is right about that! On some models the voltage regulation is shared by the ECU. There are also some cars where there is no voltage regulator in the alternator, but it is entirely controlled by the ECU.

Your Answer

Add photo

Related Questions

MX-5 Miata

Looking for a Used MX-5 Miata in your area?

CarGurus has 4,925 nationwide MX-5 Miata listings starting at $1,995.


Search Mazda MX-5 Miata Questions

Mazda MX-5 Miata Experts

#1 Michael Kane
Michael Kane
Reputation 1,840
#2 Tom Demyan
Tom Demyan
Reputation 1,060
#3 Racer_X
Reputation 380
View All

Related Models For Sale

Used Ford Mustang"
745 Great Deals out of 41,444 listings starting at $900
Used Honda S2000"
28 Great Deals out of 385 listings starting at $8,495
Used BMW 3 Series"
1,618 Great Deals out of 39,936 listings starting at $1,500
Used Chevrolet Corvette"
431 Great Deals out of 20,301 listings starting at $3,688
Used Chevrolet Camaro"
839 Great Deals out of 39,073 listings starting at $2,650
Used Honda Civic"
1,183 Great Deals out of 58,586 listings starting at $1,295
Used Porsche Boxster"
70 Great Deals out of 1,538 listings starting at $4,800

Used Cars For Sale

2016 Mazda MX-5 Miata For Sale
7 Great Deals out of 3,215 listings starting at $20,650
2015 Mazda MX-5 Miata For Sale
18 Great Deals out of 205 listings starting at $15,995
2014 Mazda MX-5 Miata For Sale
10 Great Deals out of 99 listings starting at $16,404
2013 Mazda MX-5 Miata For Sale
8 Great Deals out of 159 listings starting at $13,883
2012 Mazda MX-5 Miata For Sale
8 Great Deals out of 111 listings starting at $10,995