jayntee

The battery light has been going on and off on my car for about 3 weeks now. The first time i checked the 7.5a alt fuse and it was blown so i replaced it. The light went off for about a week and then came back on. Then my car started to lose electrical power again, and i checked the fuses and they were still good.

So i figured it was time to change the alternator because i believe this is the orignal and the car has A LOT of miles, and plus the p/s has been leaking on it. I know i should get both repaired at the same time, but didn't have enough to replace the p/s pump yet. I changed the alternator about a week ago and the battery light went off for a couple days. Since then it the light has been going on and off everytime i turn off the car and turn it back on. So today i went and replaced the battery because i figured the other battery was bad since it was about 5 years old and has been drained completely twice in the past month. The light went off then back on after about 1 minute of driving. I got home and saw that the connection to the battery was loose so I tightened that down.

I drove about 15 minutes to work and was at work for about 7 hours. Hopped back into my car, turned it on, and the light is back on.

Do you guys think it is the other alt fuse? (120a) I am going to change the battery terminals and clean on the alternator plug. Do you guys have any suggestions on how to clean on the plug safely? I was going to use break cleaner and compressed air.

thanks for your help

Legender

Not brake cleaner... baking soda mixed with water and use a toothbrush on it clean the post well. And the terminal (the clamping device on the cable) may be bad/loose/broken/corroded also. You need to look at that. In a pinch you can use coca cola to clean the battery post and the terminal. But a little baking soda and water will work. Should bubble up and fizz as it works on the corrosion. After you've cleaned the post you should use a battery post tool (you can get them at walmart or any auto parts store)... to get a new metal finish on the post to get it a better electrical connection. Essentially just a wire brush that cleans the post off really well. It has a matching end that goes into the terminal and cleans it up also. I highly recommend this.

And you really should do something about that PS pump... it will ruin your new alternator if not addressed quickly... and you'll have to do this all over again.

Gene01

You did the right thing by checking the fuses, but it would be well to also check the voltage under the following conditions:
1. Key OFF - The battery voltage under (essentially) no load should be 12.5V or higher. If it is lower, charge the battery and try again. If still low, the battery is not holding a charge and should be replaced.
2. Key ON - The voltage should not drop very much, perhaps to 12.4 or so.
3. Headlights ON - The voltage should drop a bit more, but not lower than about 12.3 .
4. Cranking - The voltage should not drop lower than 9 or 10 V. It's not as easy to measure because the car will start in a few seconds, but you should be able to get a good idea. Cranking should be rapid.
5. Running - The alternator should supply above 13.6V and rise somewhat with increasing engine RPM.
If it is lower, the alternator is not supplying adequate charging voltage, and probably needs to be replaced.
You could first try to clean the slip rings of the PS fluid, though.

LScowboyLS

the first thing I would do is replace the + battery terminal with the real Toyota one - they tend to develop hidden corrosion on the inside (hidden by the bolt)

the Toyota part number is 90982-05037 (about $14 online)

jayntee

I think i may have failing (or failed) ecu capacitors. On the way home last night (my battery light still on) the ABS light turns on and my car starts to lose power and everything becomes dim, after about a minute or so the light turns off and everything goes back to normal (minus the battery light). Same thing happens again like 5 minutes later. Luckily i was able to make it home.

I left the car sitting all day and decided to take a look at all my fuses again tonight. Started the car up and my tach is not working (it has been working on and off for the past month or so) and the cars idle is bouncing up and down like crazy.

So I am thinking it is my ecu, can anyone confirm?

LScowboyLS

except at the earliest stages, the ECU capacitors can be visually seen when leaking, so follow my instructions in the ECU capacitors thread and pull out the ECU (after disconnecting negative battery cable) and while bare-footed and wearing all cotton clothing, carefully open ECU and take some high resolution photos of the inside showing the capacitors, Yamae and I will inspect these pics as we have seen the leaking capacitors hundreds of times and can easily spot them.

but before even doing that, if this were my car, I would start with eliminating the easy things, a new positive battery terminal from any Toyota dealership (part number is 90982-05037) - and a new battery if your battery is over 3 years old, and some voltage measurements across the battery with car off, car on at idle with headlights on, and car at 2000 rpm in park with headlights on, post the voltages here.

Yamae

You'd better to check the voltage first as Gene01 is suggesting.

jayntee

I just replaced the battery like last week, so that's off the list.

Will check voltages tomorrow and thursday and post asap.

Thanks for the reply guys

jayntee

Hey guys, I know it's been a very long time, but I finally had the time to look at my car.

I got back underneath it and took a look at the connections on the alternator. The power terminal (i think. Where the one wire bolts onto the alt.) felt really crisp when i touched it. When i took a look at it, it looked like it heated up real hot and melted and gave a bad connection. I cleaned up the area and reinstalled everything, and the battery light is now off.

My question is why would this happen? I am using the correct amperage fuses and the wire is the old one that was on the car already.

TIA.