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View Full Version : SR20det battery/brake light (even after alternator change)

rancid240
06-07-2010, 11:40 AM
Background, its an sr motor that had brake/battery light on, dead battery. Charged battery (tested good), lights were still on. Took out SR alternator, replaced with re-man KA unit. Both lights are still on. Interestingly the SR alternator tested good after removal as well.

All connections appear well, alternator ground to battery has no resistance, battery posi to alternator power has no resistance. Also tested for volt drop accross both and nothing measurable.


From what I've read on this website Charging System Checks (Alternator Testing) (http://aa1car.com/library/charging_checks.htm) the battery and brake light's come on when the alternator is not giving any charge. However, the car is putting out 11v off at battery, when on its 13.5 volts, I read that you want 1.5-2v extra when alternator is on to signal that you are charging.

What I want to do is test the alternator's output to the battery light, which I am assuming is the clip harness that comes from the alternator. However, I want to know what kind of voltage I should be looking for? If its not putting any voltage out it will trip the battery light, but how much is enough to turn it off? Thanks
ecuastyle84
06-07-2010, 02:32 PM
Did you check your alt fuse?
rancid240
06-07-2010, 03:11 PM
I checked any related fuses
rancid240
06-14-2010, 12:17 AM
After looking at this and checking my wiring, I found out that my alternator clip was faulty (it was hacked up).

http://www.plmsdevelopments.com/images/rhs_wiring.jpg

So if your having trouble with your alternator charging make sure that thick wire on the connector is putting out volts with the car on. Otherwise the alternator wont put out the correct power.
Om1kron
06-14-2010, 12:55 AM
yeah looks like you solved your problem. The plug that goes to the alternator is the next one to look at if all of your connections are solid. If one wire is connected (white/red) doesn't matter if the other wire breaks. The other wire however is the one you'll want to work if indeed you run into a situation where the alternator fails or a fuse does blow so you know where else to look.
240Zfunahollic
06-14-2010, 10:20 PM
if this is an s13 chassis, check the 10 amp eng cont fuse in the box next to the battery. That was always my battery/brake light problem. I blew it several times too. I now have a reworked engine harness and havent had the problem since.
vertsilvia93
01-13-2020, 09:10 AM
if this is an s13 chassis, check the 10 amp eng cont fuse in the box next to the battery. That was always my battery/brake light problem. I blew it several times too. I now have a reworked engine harness and havent had the problem since.

which fuse was this?? I am having the same issues and I cant figure it out!
brndck
01-13-2020, 10:07 AM
which fuse was this?? I am having the same issues and I cant figure it out!

if this is an s13 chassis, check the 10 amp eng cont fuse in the box next to the battery. That was always my battery/brake light problem. I blew it several times too. I now have a reworked engine harness and havent had the problem since.

the 10a eng control fuse in the box next to the battery. :wiggle:

https://restomod.ninja/wp-content/uploads/2018/01/s13-fusebox.jpg