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Replaced new alternator twice and still have problem with charging.

Changed IC and regulator but same problem appered.

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Clean all connections especially starter and solenoid and ground from engine to frame

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Battery good, alternator good, starter good but my 1966 oldsmobile the alternator isn't charging the battery

Have you replaced the voltage regulator?
Unless you have changed the charging system and eliminated it, the alternator does not have a built-in voltage regulator like the newer ones do.
Be blessed.

Feb 06, 2013 | Cars & Trucks

1 Answer

On my 1998 v6 explorer, i had my alternator rebuilt twice, have bought a brand new one, which is still on there, replaced the battery with a new one. in-line fuse from alternator to battery is good. system...

Most charging circuits are in two sections, the section that charges the battery and the section that "turns on" the alternator when the engine starts. Your alternator has a built in regulator which is powered by a 15 amp fuse and a 7.5 amp fuse that also handles the gauge on the dash.
These circuits would need to be checked with a meter.

Dec 15, 2012 | 1998 Ford Explorer

1 Answer

I changed the battery yesterday and started the truck twice. The 3rd time there was no juice to turn it over. Regulator or alternator?

usually regulator. Charge battery for a few hours. Start engine and see if the voltage is 14 1/2 approx. That would mean system is charging and it's a bad battery

May 22, 2011 | 1985 Ford F150

1 Answer

I have an 86 toyota pcickup battery charge light is on have good battery and replaced alternator twice.

i think you have an external voltage regulator in that year , ck that first . The easy way to tell if it has an external regulator ,if it has carburated it has an external regulator if its fuel-injected its internal regulator in side the alternator.Have you checked to see how much voltage the charging system is putting out at an idle ? It should be around 13.5 volts to 14.5 volts any less then 12.5 charge light won't go out.

May 05, 2011 | 1986 Toyota Pickup 4WD

2 Answers

What are some techniques to fixing the alternator?


To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.
  1. NEVER reverse the battery connections. Always check the battery polarity visually. This is to be done before any connections are made to ensure that all of the connections correspond to the battery ground polarity of the car.
  2. Booster batteries must be connected properly. Make sure the positive cable of the booster battery is connected to the positive terminal of the battery which is getting the boost.
  3. Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction for which they were designed.
  4. NEVER use a fast charger as a booster for starting the car.
  5. NEVER disconnect the voltage regulator while the engine is running, unless as noted for testing purposes.
  6. Do NOT ground the alternator output terminal.
  7. Do NOT operate the alternator on an open circuit with the field energized.
  8. Do NOT attempt to polarize the alternator.
  9. Disconnect the battery cables and remove the alternator before using an electric arc welder on the car.
  10. Protect the alternator from excessive moisture. If the engine is to be steam cleaned, cover or remove the alternator.
TESTINGThere are several checks that can be done with inexpensive equipment. The first thing to do is to see if the discharge warning light on the dashboard lights when the ignition switch is turned on. If it is not lit, check for blown fuses, a blown out bulb itself (The system will not charge with a bad bulb) or bad connections.
If the warning light does light with the ignition switch on, but stays on with the engine running, check for a loose (or missing) belt, a loose or faulty battery cable, corrosion, a blown fuse or fusible link or a shorted or open wire.

If everything seems to be good (including the battery), but the charge light is always on, then the alternator itself probably is to blame. This does not mean the whole alternator needs to be replaced. Many times, the IC regulator can become faulty and cause the no-charge condition. There is a way to determine whether just the IC regulator or the whole alternator should be replaced.

The alternator can be "full-fielded;" that is, the F terminal can be shorted to ground, making the alternator think there is a heavy load on the electrical system. If the alternator starts putting out when the F terminal is shorted to ground, then the IC regulator is probably faulty. If the alternator still does not put out when the F terminal is grounded, then the whole alternator should probably be replaced. It can be concluded that the alternator is "putting out" by observing the voltage of the battery. The system is charging when the battery voltage is approximately 14-15 volts. If it is only 12-12.5 volts, something is wrong. If the charging voltage is too high (more than 15 volts, the battery smells like sulfur or frequently runs out of water or the bulbs in the vehicle burn out too frequently, then the IC regulator is probably faulty (See Regulator).

Check the alternator and IC regulator by performing the following:
  1. Ground the F terminal on the alternator.
  2. Start the engine.
  3. Analyze the voltage, using the information above.

Fig. 1 Checking the alternator and IC regulator 2S-E, 3S-FE and 3S-GE engines shown


Fig. 2 Checking the alternator and IC regulator 4A-FE, 5S-FE and 3S-GTE engines shown

Hope this help (remember rated this).

May 17, 2010 | 1987 Toyota Celica

2 Answers

I replaced the alternator twice and the new alternator is not working?

It probably isn't the alternator that is bad, but rather the voltage regulator, which by the way is in the computer behind the battery.

Oct 30, 2009 | 1990 Dodge Grand Caravan

1 Answer

Voltage fluxuations. I've replaced the alternator twice and the battery is new yet the alternator is not charging the battery. As a result the battery voltage goes down until it finally is drained. What...

check for open wiring first around the alt. sometimes will tear the insulator and arc off.You can see this at night in the dark.Most regulators are in the alternator.

Sep 25, 2009 | 1991 Plymouth Grand Voyager

1 Answer

Why won't my new alternator charge my new battery

the power wire for that lays on top the intake probly has bad spot drawing out the current

Apr 08, 2009 | 1995 Ford Mustang

1 Answer

1992 Nissan Pathfinder charging problems

How long did the 2nd alt. last before it died? The voltage regulator is, I believe, attached to the alternator. Have u had the voltage regulator checked?

Jan 04, 2009 | 1992 Nissan Pathfinder

1 Answer

Regulator problems

The computer regulator is very hard to burn out. Just make sure all your battery cables are good and the alternator fuse is good. There is a fuse.

Nov 22, 2008 | 2000 Dodge Durango

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