headlights draining power, what should i do?

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supraian

New Member
Jan 2, 2006
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san diego
my headlights are draining my battery i have a lot of other accesories (amp, fans, gauges) but i've narrowed it down to the headlights taking the most. with all other accesories on its about 13.9 once i turn the headlights on i drop to around 12.2-12.4. these are taken at the battery. from the alt they are about .2 volts higher. i have a new battery and tried another battery with the same results. the alt is a new 100amp and my old alt was doing the same thing. the wires at the back of the alt are a little cracked i may rewire those but most important where are the grounds for the headlights and has anyone rewired them?
 

blackgamer16

Supra Driver
Apr 27, 2005
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Sooner Country
RHDMK3 said:
Did you check the wiring? It might be shorted out to something.


You could also try this... take out a fuse at a time.. and than see if drain goes away- when u notice the drain is gone on that one particular fuse that you took out- see whats all wired up to that one fuse and then work your way through each component till you find your drain. I hope that makes sense, i apolize if not.. lol

Blackgamer16
 

blackgamer16

Supra Driver
Apr 27, 2005
243
0
16
39
Sooner Country
supraian said:
yeah makes since, i'd be doing these to the fuses under the kick panel correct?


There are fuses on both pass + drivers kick panel. Also there are 8 fuses/relays behind your battery. Check them out also.. If it was me i would start with the fuses from the baterry, than move to the drivers side and so on.

MOST IMPORTANT.. i can't remember exactly the time for the computers to go to sleep i think its 30 mins once you take the key out of the cylinder. and than start lookin for your drain.

If you open a door/trunk etc. the 30 mins start all over again and it be pointless testing things since you just woke up a computer. Just keep your windows down and tape up ur door switch to the pressed position so you bypass that switch for accessibility(sp).

Blackgamer16
 

supraian

New Member
Jan 2, 2006
66
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0
san diego
i'm starting to wonder if i got another bad alt, i replaced the wires going into the back of it (they weren't in very good shape) and went through just about every fuse/wire. the headlights drain the most but i did notice all others drain a bit too and i'm getting very low readings at the alt now, around 12.5v. what controls how much charge the alt produces? any way to test if i have a bad alt?
 

Suprawannabe

meh... im lazy
Oct 27, 2005
122
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Denver, CO
supraian said:
i'm starting to wonder if i got another bad alt, i replaced the wires going into the back of it (they weren't in very good shape) and went through just about every fuse/wire. the headlights drain the most but i did notice all others drain a bit too and i'm getting very low readings at the alt now, around 12.5v. what controls how much charge the alt produces? any way to test if i have a bad alt?


See what voltage is coming out of your alternator then see what it is at your battery. I'm guessing you still have the wireharness that came with the car so you could just have high resistance through the wires.

Easy way to check which side of the circuit your problem might be is too get a DMM and put your positive lead on the alternator power bolt and negative lead on the power side of the battery. For the ground side of the circuit positive lead on negative battery post and negative lead on the alternator case
 

supraian

New Member
Jan 2, 2006
66
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0
san diego
got the alt checked they said it was fine. where do the accesories ground? i'm asking cause i can bump my system and no drop, fans not much of a drop, and they are on their own wires. so i'm thinking there must be some resistance in the wires for the accesories it only drops to around 12 if the headlights or climate control is on, and if they are both on down to around 11.

i also grounded the alt bracket didn't make a big difference
 

Suprawannabe

meh... im lazy
Oct 27, 2005
122
0
0
Denver, CO
supraian said:
got the alt checked they said it was fine. where do the accesories ground? i'm asking cause i can bump my system and no drop, fans not much of a drop, and they are on their own wires. so i'm thinking there must be some resistance in the wires for the accesories it only drops to around 12 if the headlights or climate control is on, and if they are both on down to around 11.

i also grounded the alt bracket didn't make a big difference

OH, I kinda read your post wrong. I was thinking you were getting 12.8 at idle with no accessories. To make sure though you could use the TSRM to find out all the test you could do for the alternator. I was kinda in the same boat but worse so I just replace the whole engine wire harness and no prolems since. I would just pull up the wire diagram for the headlights and start cheacking everything for peace of mind. Good Luck!
 
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