crx_88_si

Ok.,. i'm thinking alternator, just want to make sure before I go get one...

this morning, i started the car up, started fine, not warning lights on. I go inside for 5 min while the engine warms up and defrosts the windows. I come back out and the battery light is on. My voltmeter reads 11v. I rev the engine to 2.5-3k and the light goes off, as soon as revs drop below 1.5k the light comes back on. Happens every time i rev it.

Well, i've seen the volts go low sometimes on my car with alot of elec load so i think maybe it just needs to run a bit w/ the engine speed changing to charge. So I start driving. No more than 300ft later my volts are down to 10v and the light is still on. I stop, go back home and get the wife to drive me in.

Alternator?

Thanks

Terry36

I had the same problem on my 200SX, it was the alternator.

therealtime

I had the same problem on my 87 civic wagon... alternator.

-tony

Kaan

iTrader: (3)

just test it... start it up and then unhook the battery... if the car dies... its your alternator

WWDTrackRacer

Intermittent battery light. No problems whatsoever. Alternator
always charged battery. Eventually -- the alternator developed
a 1amp drain when shut off. But when running, it charged everything
just fine. wierd.

yah but expect to replace the alt soon.

crx_88_si

the light isn't really intermittent. It stays on constantly @ idle, but when i rev the car it goes off (volts still ~12v (closer to 11v)).

Pay2play killa

yes its your alternator; the "battery" light is actually wired to your alternator so when you dont have enough juice coming out of it you get the light. System voltage should be nearly 14v at idle and all the way across the revs unless you have a massive load on it.

Time for a new alt $10 in the classifieds should do you good

RCautoworks

Thats not good at all, you could blow fuses, and in newer cars you can blow ecu's .

Do it the right way, test the battery with the car off, should be around 12.20v, turn on the car and the volts should go up to 14v.

There are other test as well.
TESTING
Voltage Drop Test
NOTE: These tests will show the amount of voltage drop across the alternator output wire from the alternator output (B+) terminal to the battery positive post. They will also show the amount of voltage drop from the ground (-) terminal on the alternator.

A voltmeter with a 0–18 volt DC scale should be used for these tests. By repositioning the voltmeter test leads, the point of high resistance (voltage drop) can easily be found. Test points on the alternator can be reached by either removing the air cleaner housing or below by raising the vehicle.

Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
Start the engine, let it warm up to normal operating temperatures, then turn the engine OFF.
Connect an engine tachometer, following the manufacturer's directions.
Make sure the parking brake is fully engaged.
Start the engine, then place the blower on HIGH, and turn on the high beam headlamps and interior lamps.
Bring the engine speed up to 2,400 rpm and hold it there.
To test the ground (-) circuitry, perform the following:
Touch the negative lead of the voltmeter directly to the positive battery terminal.
Touch the positive lead of the voltmeter to the B+ output terminal stud on the alternator (NOT the terminal mounting nut). The voltage should be no higher than 0.6 volts. If the voltage is higher than 0.6 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.6 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each ground (-) connection in the circuit to locate the excessive resistance.
To test the positive (+) circuitry, perform the following:
Touch the positive lead of the voltmeter directly to the negative battery terminal.
Touch the negative lead of the voltmeter to the ground terminal stud on the alternator case (NOT the terminal mounting nut). The voltage should be no higher than 0.3 volts. If the voltage is higher than 0.3 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.3 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each positive (+) connection in the circuit to locate the excessive resistance.
This test can also be performed between the alternator case and the engine. If the test voltage is higher than 0.3 volts, check for corrosion at the alternator mounting points or loose alternator mounting.
Output Voltage Test
Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
Perform the voltage drop test to ensure clean and tight alternator/battery electrical connections.
Be sure the alternator drive belt is properly tensioned.
A volt/amp tester such as the VAT–40 or an equivalent, which is equipped with a battery load control (carbon pile rheostat), full field tester and an inductive-type pickup clamp (ammeter probe) is used for this test. Make sure to follows all directions supplied with the tester.
Start the engine and let it run until it reaches normal operating temperature.
Connect the VAT–40 or equivalent and turn the selector switch to position 1 (starting). Make sure all electrical accessories and lights are turned OFF.
Set the parking brake, place the transmission in Park or Neutral, and start the engine. Operate the throttle and hold the engine at 3,000 rpm with all accessories in the off position, until the radiator cooling fan comes on. Then allow the engine to idle for 15 seconds.
Raise the engine speed to 2,000 rpm and check the voltage. If the voltage is less than 15.1 volts, go to the next step. If the voltage is greater than 15.1 volts, replace the alternator.
Allow the engine to idle with all electrical accessories turned off. Turn the selector switch on the VAT–40 or equivalent to position 2 (charging).
Remove the inductive pick-up and zero the ammeter.
Place the inductive pick-up over the B terminal wire from the alternator, making sure the arrow points away from the alternator.
Raise the engine speed to 2,000 rpm and read the voltage. If the voltage is 13.5 volts or greater, go to the next step. If the voltage is below 13.5 volts, replace the alternator.
Apply a load with the VAT–40 or equivalent until the battery voltage drops to between 12–13.5 volts. If the amperage output is 75 amps or more, the charging system is good. If the amperage output is below 75 amps, go to the next step.
WARNING
When performing the full field test, do not allow the voltage to exceed 18 volts as damage to the electrical system may occur.


Perform a full field test by attaching the full field probe from the VAT–40 or equivalent into the full field terminal inside the full field access hole on the back of the alternator. Hold the engine speed to 2,000 rpm, switch the field selector to the A (Ground) position, and check the amperage reading.

Another one I got from a GM manual
TESTING
Voltage Test
Make sure the engine is OFF, and turn the headlights on for 15–20 seconds to remove any surface charge from the battery.
Using a DVOM set to volts DC, probe across the battery terminals.
Measure the battery voltage.
Write down the voltage reading and proceed to the next test.
No-Load Test
Connect a tachometer to the engine.
CAUTION
Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is optional and an added safety measure.


Turn off all electrical loads (radio, blower motor, wipers, etc.)
Start the engine and increase engine speed to approximately 1500 rpm.
Measure the voltage reading at the battery with the engine holding a steady 1500 rpm. Voltage should have raised at least 0.5 volts, but no more than 2.5 volts.
If the voltage does not go up more than 0.5 volts, the alternator is not charging. If the voltage goes up more than 2.5 volts, the alternator is overcharging.
NOTE: Usually under and overcharging is caused by a defective alternator, or its related parts (regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Further testing, which is not covered by this book, will reveal the exact component failure. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.


If the voltage is within specifications, proceed to the next test.
Load Test
With the engine running, turn on the blower motor and the high beams ( or other electrical accessories to place a load on the charging system).
Increase and hold engine speed to 2000 rpm.
Measure the voltage reading at the battery.
The voltage should increase at least 0.5 volts from the voltage test. If the voltage does not meet specifications, the charging system is malfunctioning.
NOTE: Usually under and overcharging is caused by a defective alternator, or its related parts (regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Further testing, which is not covered by this book, will reveal the exact component failure. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.

Tyson

get a new alternator. when the "battery" light (its really called the "charge warning" light, has nothing to do with the battery) comes on, your alternator has issues and likely needs replacement.

and since you already tested it as 11V, its time to replace. you did all the right things. theres no further testing needed. you can be certain replacing the alternator will solve your problems.

however, i really recommend you stay away from autozone alternators. theyre really crap. i dunno what they do to consider "rebuilding" the alternators they sell, but they always have problems. if it wasnt the lifetime warranty, i would not continue to use mine. ive had so many problems, i can repalce it under 30mins and in the dark. i really recommend getting a new one directly from honda, majestic has theirs listed at $182. i think its a good deal.




Modified by Tyson at 12:43 PM 11/23/2005

hotboxedcrx

It sounds like your alternator, could also be a slipping alternator belt,

I have a alternator IM me if interested.

crx_88_si

Problem found, loose battery terminals! ::angry::

ghost_ryder35

very informative post 90blackcrx.... THANKS!

rerun07

how do u fix loose battery cables? i got a new battery and the positive connector is loose. i can't tighten it up any more.

Tyson

shove another piece of metal in between.

crx_88_si

ya u could do that.. i just replaced them w/ new ones...

WHAT TEH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_88_si &raquo;</TD></TR><TR><TD CLASS="quote">Problem found, loose battery terminals! ::angry::</TD></TR></TABLE>

lol. after everybody insisted on it bein' tha alternator, it turned out just bein' a loose connection, lmao.

_taF

crx_88_si

actually. lol, about 2 weeks later the light came on again and i saw my volt meter drop to ~10v.

replaced the alt. problem solved. for a few more weeks. its not an autozone cuz i dont have autozone in canada, but it was a rebuilt unit.

Well a few weeks after replacing that one i was driving and noticed my dash lights were REALLY bright, cool, thats what its supposed to look like. (actually looked nice) thats when i glanced at the volt meter, pegged @ 19v (probably more) and i could smell a not normal smell. Anything off idle was max out the volts, idle = 14v.

so, returned for another, been fine since.