I am guessing the problem is in the alternator/regulator. From back in the day when I did a lot of work on my cars, I recall that the way to test it was to check the voltage across the battery with the engine running. If it shows less than about 14 volts (a bit lower with a drain like the headlights) then it's the alternator. Is that correct?
In the old days, I'd have replaced the regulator, but it is my understanding that now you have to replace the whole alternator. And it used to be a pretty easy job to change the alternator - is that still true? Thanks!
2007-03-22 06:15:10 · 9 answers · asked by Gary B 5 in Cars & Transportation ➔ Maintenance & Repairs
I should note that the alternator DOES charge the battery, just not very well. If you leave the engine run for a while, the battery gets charged up enough to start the car again. But after a couple of days, it goes out again.
2007-03-26 05:34:22 · update #1
You may have a parasitic drain somewhere. Find a shop that has a Minute Man tester, It will test entire electrical system, even the diodes in the V regulator. Then replace accordingly.
Just for fun, put the positive lead (of your meter) to the battery positive post, randomly place the negative lead onto battery surface. This will show current loss that occurs on top of the battery, from moisture and dirt.
A short would blow a fuse. Unhooking battery will not fry the computer (a.k.a. ECU), it will reset driver info, and in rare cases set off air bags, do not back feed electrical system with a battery saver...very bad idea, unless you want new airbags.
Clean battery posts and connectors, check electrolyte levels. Old batteries do go bad, check the install date on the battery case.
2007-03-26 05:21:35 · answer #1 · answered by High-wire 4 · 0⤊ 0⤋
Check to make sure all your battery connections are clean and tightened. You could try a voltage drop test on your battery. You will need a multimeter, digital is easier to read and more precise, place the red probe on your positive, the black on your negative and have a friend or someone try and start the car, make sure the battery is fully charged when you do this. when cranking the voltage shouldn't drop below 9.6 volts, if it does it means your battery is bad, also if you have the car running check your alternator output the same way if you cant reach the terminal directly on back of the alternator, it should read betwenn 13.2-13.8 depending on your alternator/regulator, usually if its higher it means your regulator is bad and is overcharging your battery and can lead to the same problems, and yes pretty much no one will sell you a regulator its a replace as a unit job. Also be wary of just disconnecting your negative cable and seeing if it dies, on alot of newer cars once the ECM loses its source voltage from the battery the car will die anyway, no matter how good your alternator is, I know yours is a 91 and not largely subject to that, but mostly for everyone that answered with that solution.
2007-03-30 01:59:20 · answer #2 · answered by cm2_r_u 2 · 0⤊ 0⤋
Sounds like you could have a bad battery. Check all of the connections to and from battery for corrosion. Check the battery with a voltmeter with the car shut off. It should be 12.8 to 13.4 volts. If it is below 12 volts than the battery could have a dead cell. I always start at the battery. I would then check things like belt tension, overall temperature of the alternator with engine running, and the fuse panel. If you have a blown ECM fuse on some cars the charging system doesn't work. If you have to replace the alternator you won't have rocket science looking you in the face. They are fairly simple for any person with mechanical ability.
2007-03-30 04:39:31 · answer #3 · answered by Bryan A 3 · 0⤊ 0⤋
Yes it is probably your alternator. I would try changing it out after you have had the battery checked first. Your battery could have a dead cell in it making you think that it is not charging right. You are right they don't make them like they used to. Everything is made together now to save space and weight. It should charge about 14.5 volts or so depending on your alternator.
2007-03-29 16:17:59 · answer #4 · answered by dude 2 · 0⤊ 0⤋
It could be that your alternator belt is loose. You can check the alternator by : starting your car/truck, and, while the motor is running, take the battery cables loose. If the car keeps running, it is not a bad alternator. If it dies, replace the alternator.
2007-03-29 16:58:05 · answer #5 · answered by Jennifer N 3 · 0⤊ 0⤋
yeah, things are still the same... you could just take the negetive side off the battery while its running and if it dies than the alternator is bad... ( WARNING: Turn off car before reattaching battery cable or you could fry your cars computer )
2007-03-22 06:31:54 · answer #6 · answered by Aaron M. 5 · 0⤊ 0⤋
Check the poles on the battery for corrosion and clean them off and make shore that they are tight
2007-03-28 10:42:59 · answer #7 · answered by z 2 · 0⤊ 0⤋
try your ground wires . in order for your car to charge the battery the ground wire and hot wire should connected good.
2007-03-30 02:13:39 · answer #8 · answered by jessica w 1 · 0⤊ 0⤋
Maybe there is a short somewhere in the system
2007-03-22 06:22:13 · answer #9 · answered by Anonymous · 0⤊ 1⤋