So I have had my 95 sc400 for almost a year now. And just recently I have this power problem. It happens once and a while, not all the time. I tried to see if there was something causing it, like weather and moisture, but it is different every time. When I drive my lights will dim when I do anything (like if the radio is on, roll up the windows, brake) Sometimes it gets so bad that my battery light will come on for a second and then it goes off. And my radio will flash on and off. So I thought originally that it was my battery, maybe that it was bad and I just need some extra juice. I went and got it tested. It turned out to be just fine. So then I thought that it was my altenator. I had my Dad unhook my battery and start it and it started. So I know that my alt is good. But when he unhooked my battery he noticed that my battery cables were really corroded and were barely attached to my battery. So he replaced them. Everything went good for a couple weeks and I thought that the issue was fixed. But then it starts doing it again. It seems like it does it more when it rains or snows or foggy, which makes me think that I have an exposed wire somewhere and it is shorting out. But one day when it was pouring out it never did it and another time when it was a beautiful day, not even a cloud in the sky it did it again.

So I am thinking that it is a short somewhere. Just wondering if this is a common problem and if it is, can someone tell me which wires to wiggle first.

 

Its kind of hard to get to but you should make sure the heavy battery wire is tight on the back of the alt. and the plug is pushed all the way in. Follow the ground cable of the battery all the way down to where it attaches at the front bottom of the engine and make sure the connection is clean and tight.

 

That seems to be a battery related problem. Check the main ground from the battery to the chassis. Or you can 2 extra ground wires, maybe a 2-4 gauge. 1 is from the battery connecting to the chassis, and the other is from the battery connecting to the engine. There's a lot of threaded holes there. This is an easy way to test and actually to enhance the electric conductivity of your car.

If doing the above won't solve the problem, then perhaps it's the battery even though it's tested working. My experience is I had a battery that's tested perfectly, however, I know it's bad. If I jump-started the battery or charged with a battery charger, it worked. But if I didn't the drive for 2 days, then it died. Another thing is if I turned on the stereo while driving, the lights dimmed out. I took it back to Autozone and they argued that it's working perfectly due to the test result. I told them that's not true because I just took it out from a running car, that's why the charge is full but it's not keeping the charge.

I then took it home, connected it back, turned on the radio until it's drained out to 7.5 volts, took it back. And of course Autozone tested it and it's too low for a working battery. They replaced a new battery and I didn't have any issue whatsoever until now.

To test the alternator, start the engine and let it run, disconnect the battery. If the engine still runs for awhile, then it's not the alternator. Or you can take out the alternator and take it to the alternator shop for them to test it out. It's not too hard to take it out.

 

I had a cutlass that did the same thing and it turned out that my alt belt was not tight enough.

 

We've got auto. belt tensioners, so most likely our belts will be tight.

 

Oh! dawm i fergot i had that..hehe

 

i have a problem.. my battery light is constantly on...also that "taillight out " indicator, even though all my lights work perfectly....alternator?

 

Check the negative battery terminal It was my issue it was corroded inside the insulation I looked fine but it would create resistance and our cars are very sensitive to ground. You wont belive this but you just cant buy the cable from lexus. there was a post that you can buy one from GS300 but still do you want to pay 90+ for a stupid ground cable? This is what I did I was looking around at walmart one day and I found a cable with a crimped end battery terminal on one end and and hole lug on the other. I am not home now bit it was about 16 to 18 inches long. If you follow the ground cable back you will notice that there is a grounding point 16 to 18 " from the ground terminal remove that screw and put the hole lug on that one and put the other side on the terminal. Them measure the voltage at the battery and make a note of it. Put a volt meter on the positive of the battery and measure the voltage across the ground points on the engine they all should match the inicial voltage reading that you took at the begining. Its about a half hour job