does anyone know what will cause 12 volts to constantly pull from battery when key is in off position. I disconnect the ground from the battery and put a meter between the terminal and the post, to my understanding it should read 0 but I read -12.2 I have pulled all fuses and relays yet it is still pulling any suggestions?
electrical prob with my 91 miata
#1
Posted 03-17-2014 05:06 PM
#2
Posted 03-17-2014 05:22 PM
Does this current drain occure with the battery on/off switch in the on position or the off position?
Which wiring diagram did you use when installing your battery on/off switch or which wiring diagram did the installer use.
#3
Posted 03-17-2014 05:33 PM
How about, is this a regular street car or a race car ?
J~
#4
Posted 03-17-2014 05:36 PM
I just got this car 3 days ago and it is factory, so I don't have a on off switch but after trying everything everyone has suggested I am planning to install a kill switch so it don't drain every battery I get. at this point I am at a loss.
#5
Posted 03-17-2014 05:42 PM
There is a main fuse box (9 fuses) under the hood passengers side ??? and there is a fuse box (10 fuses) under the dash, drivers side.
Seems as tho you should be able when it's dark outside or in a garage have the battery cable connector finger loose and gently touch the battery post and with a current draw you should see a slight blue spark. Start in the fuse box and pull one fuse at a time and check for the little spark. If you have spark, put fuse back in. When no spark, your well on you way to finding the issue. I have used this process with vehicles that have a computer and it works.
#6
Posted 03-17-2014 05:42 PM
Measure the current, not the voltage. To protect your ammeter, first try putting a test lamp where you were putting the voltmeter. If the test light illuminates you have a draw that will be higher than the scale of some meters. Nearly full voltage will be indicated on a DVOM even with a very low draw. The computor has a keep alive continuous draw. Sometimes there is a minor draw from the altenator. You should see less than 50 mA draw.
#7
Posted 03-17-2014 05:58 PM
I tried the alternator and that didn't change the draw....but I may not have had my meter on the right setting so I will check this and try again
#8
Posted 03-18-2014 08:40 AM
Digital clock, Radio preset memory, any add on electrical items.
All will draw 12 volts, the important measurement is how many amps.
Dave
Dave Wheeler
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#9
Posted 03-19-2014 12:01 PM
does anyone know what will cause 12 volts to constantly pull from battery when key is in off position. I disconnect the ground from the battery and put a meter between the terminal and the post, to my understanding it should read 0 but I read -12.2 I have pulled all fuses and relays yet it is still pulling any suggestions?
Just to rule out the not-so-obvious....
Friend of mine had the same issue. He had just bought the Miata and wasn't very familiar with it. Long story short - turns out he wasn't turning the key ALL the way back to the off position. He was able to pull the key out at the #1 position (which powers on the electricals) and thought that was as far back as it went. I got in and cranked it one position further.
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