88 SE


Problem #1 : While driving with my lights on and stereo on (medium loud), I push on the brake and I watch my voltage go down to around 12.5v on my meter(in car). At the same time, I stereo power completely cuts out then back on 3 seconds later. I *HATE* this.

Yes, I tested the battery. It's good.
Yes, I tested the alternater. It's very good.

I'm starting to think I have a short in a wire or two somewhere in the brake electrical system. And I know nothing about how to find a short or whatnot.


Problem #2: This might be related to the first problem. I dunno. But I can't play my CD Player that loud in the car. If I do, it cuts out like above. :|


Any suggestions, links, pics would help a ton.

Thank you for your time.

 

This is a very common problem covered before. You may wish to search next time, where you would have found:

Your alternator is not good if it is dropping to 12.6 or lower when your current draw is up.

Bad alt, repair or replace.

who tested it for you??? how in the world did anyone come to the conclusion that it is "very good"?

Any time the car's electrical system dropps under 12.6 volts, the car is only running on the stored charge in the battery.

and a short in the brakes would blow the BTN or other fuse. There is no such thing as a short that just draws too much current, but doesn't melt wires or fuses.

 

I got it tested at AutoZone.

I'm not sure of the EXACT voltage, but it does drop to around 13 volts. Maybe my meter in the car is bad, I don't know.

But I ended up fixing the problem.

The idiot that had the car before me didn't ground the CD Player. :|

Remember guys, always check the simple things!

 

That in no way would cause your problem, and the CD would ground through the antenna cable as well as the factory mounting brackets (if they were used).

And the voltage meter on the dash is what the interior of the car is seeing for voltage. It is very rare for it not to work correctly if the other gauges are.

 

I am not meaning to hijack the thread, but I can relate to this problem too. I noticed one day that my voltage was in the 12.5 range and had it tested at AutoZone as well. They said battery and alternator was fine too. For curiosity... if their machine says battery and alternator are fine, why should I worry?

 

I wanna jack the thread..

Ice.. on my buddy's S5.. the only gauge in the car that doesn't work is the voltage and it has not since he got the car with only 60K miles on it or so.

Is there maybe somthing simple that could have just come unpluged?

 

Probably loose screw on the back. Just pull the screws at the gauge and set them in again.

Not working at all is different than working poorly as TheHunt suggested in his case.

 

If their tester is only testing the diodes/rectifers, then even if the alts voltage output is low, the alt will test ok.

The tester should be testing load and maximum output based on load (as well as the diodes).

But its pretty easy to test yourself. Just use your handy dandy digital multi-meter and see what the voltage is at the alt with no load (should be 14.4 volts or better).

Then test again with every electrical device you have in the car on (even the rear defrost and brakes). If the second test is showing less than 13.5 volts, the alt is bad!

 

Heh, okay. That makes more sense to me now. I remember watching the display on the screen of their machine when he was testing the alternator. Something to the effect "diode state OK." My voltage is 12.5 or so with almost no electrical accessories on, so I cannot imagine how long my battery is going to last if I start doing a lot of night driving.

 

*EDIT*

I meant that I fixed my stereo proble.

But the voltage still does drop when I put on the brakes.

I'll have to check the voltage tomorrow.

14.4 volts with the car idleing...correct?

 

Yeah, 14.4 with nothing on, just the engine running. Use a digital multi meter ($20 - $100 at radio shack depending on how fancy you want to go) at the alts output, so there can be no confusion on the wiring.

No electric fan, no radio, no lights, no wipers, no defroster... just the engine running (actually even with a moderate load it should be simular, but we are testing for absoutes here).

 

How do I test the alt output? Is it the boot on the top or the plug in the back?

 

The boot covering the 8mm nut.

 

Sweet, thx guys

 

With my new alt I ran 13.1 to 13.5 at the highest (digital display on the turbo timer) Untill I did the fuel pump and now its all crazy(lowest 11.4 to 13.6 highest) Before the new alt I ran like 11.9 and 12.8 at high points.

 

HAHAHA...I'm seeing ~12.85 @ 3K....

It drops close to 12.25 @750...no wonder damn thing tries to stall...

 

You have to assume the counter person knows how to use the machine properly though.

Hugues -

 

Woo hoo. I now get 13.9 volts with the pump rewired. But I havent driven the car yet (to hot out). I hope they wont drop after becuase they usually do.

 

pm me or email seanyarroll@aol.com if you are interested in buying a 3rd gen alternator with a double alternator pulley fo cheap.

 

Pmed you!