Question about 1988 Volkswagen Fox

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Alternator when warm over charges 16 17 volts is regulator inside

I tried a second used alt that i have and same thing 16 volts after warm and rpm up 2000

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Are you boiling your battery?
are you having starting problem?
a shorted battery will cause you alt to charge very hard.

Posted on Sep 24, 2008

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How do I test to see if my alternator is bad? The dashboard lights: Gas, batt, and brake light all came on randomly. Theyll go off at 2500 RPM and my volt meter reads somewhere in the 9 volts range.


9 volts isn't enough my friend. You need about 14 to14.5 at a fast idle. Get a hand held automotive volt meter/tester and put the two clips on the two battery posts. Read the voltage without the engine running. Then start up and read the voltage at 2500 rpm. If the voltage is 12-13 at idle and 14 or so at 2500 then the gauge is faulty. If the volts are barely different to the static voltage or lower then the alternator is basically dead. The vehicle systems may play up when the volts fall below a certain level. I can't comment on the 02 sensor but that may be an independent fault. Some alternators have replaceable brushes or regulators complete with brushes. If you are handy with tools download some info on swapping the brushes/regulator or consult the workshop manual because the brushes are a few bucks and half an hour to change. If the alt has done a high mileage there will be wear on other components, bearings etc and a replacement would be a better long term bet. Check out your local parts store or go online to a Japanese auto spares site.

May 02, 2015 | 1993 Isuzu Trooper

2 Answers

How do I replace a voltage regulator on a 1995 rodeo


which engine, ?
let me guess, battery will not hold charge, battery good.
idle at 800 rpm hot, battery voltage not 13.3 to 15vdc. so charge failure and lamp glows, charge. in dash? or not glow?

so you didnt check the 3 fuses and CB yet?
seen here.
and the charge relay? seen here,
got 12vdc on all back terms of alt?
and 0v running at blue-white wire of alt pin.
use a voltmeter and find out whats going on.
the record on this forum is 5 alternators swapped out. (all in vain)



25406995-03s3gpofdgkqnuacwmw51svl-4-0.jpg

Feb 08, 2015 | 1995 Isuzu Rodeo

2 Answers

Battery not being charged by alternator. Is it the alternator, or the voltage regulator? How do I determine which?


The regulator is inside the alternator, Pull the alt. and get it bench tested.

Mar 03, 2011 | 1990 Ford F150

1 Answer

2005 silverado z71 5.3. Under normal acceleration all lights will pulse rapidly (at least once a second or faster). Checked alt output at idle- 15.3/15.5 Didnt have a second person to throttle it to check...


Yes,it is,the alternator is charging to much,this can lead to other component failures.Have the alternator changed,not just the regulator in the alternator,if a diode has burned threw,it can,and most likely is,putting out some ac voltage,witch is very bad for the ignition system,and it will put ac voltage in the battery.The pulsing is from ac voltage,not just a dc overcharge.The alternator should be 13.65 volts,to 14.25 volts,at the battery.Most of the time,when there is a pulse,in the lighting,and the alternator is charging around 15 volts,there is ac volts present.so this means,the battery would need to be changed also,to prevent any other problems.I hope this was helpful,and if so,please let us know,thank you.

Jan 03, 2010 | 2005 Chevrolet Silverado 1500 2WD

1 Answer

2000 astro van Battery and alternater are both new and checked out to be in working order. I am only getting 12 volts charging with the motor running should be 14 to 15 volts. In desperate need of ideas of...


You may have a voltage drop in the battery feed to the Alternator through the fuse link and into the battery. Check the charge rate at the battery feed on the Alternator, it should be at least 13.8 volts, if it is, locate the fuse link and check it there on both sides of the link, if its still good, follow the cable back to the battery checking the voltage as you go. If you find that the voltage suddenly drops across a connection or the fuse link, remove and clean the connection or replace it if possible. If the voltage at the back of the Alternator is less then 13 volts, then the new Alternator may be faulty. If the voltage is higher then 15 volts, then the Battery feed to the Alternator is bad and MUST be fixed. Check these voltages with the engine running but watch out for moving parts ( fans etc). If you think the battery feed to the Alternator is bad, shut the engine down and recheck the voltage at the Alternator, it should be at least the same as it is across the battery. If there is no power to the Alt when the engine is off, start at the fuse link, checking for voltage and trace back to the alt until you lose the reading. If you get no voltage at the fuse link, track it back to the battery. The voltages at the battery and Alternator should be the same or only have a difference of half a volt, any more and you need to locate and fix the bad connection. DO NOT run the Alternator without the load of the battery for extended periods as this will damage the Alternator. The Alt needs the internal resistance of the battery to function correctly. If the voltages from the battery to the alt are correct, check the regulator wiring. If memory serves, there are two small wires to the alt which are in a small plug into the alt and one thick cable which connects to a bolt on the alt. The thick cable is the battery feed, the two small cables are the regulator feeds. One small cable operates the warning lamp in the dash cluster and the other is another battery feed which gives the regulator an indication of the charge rate AT THE BATTERY so if this one is missing the regulator will also cut out. The warning lamp wire serves as an indication to the regulator that the ignition is turned on and makes the alternator charge. This lamp should be on with ignition on but engine NOT running and should go out when you start the engine. If this lamp does not light up at all, suspect a broken or missing warning lamp connection or faulty regulator.A blown warning lamp bulb will also prevent the alt from working, this is because the bulb is fed with power and is grounded at the alt through the regulator and exciter diodes, feeding the regulator with power until the engine starts, then the alternator output essentially puts power to both sides of the diodes causing the lamp to extinguish. A diode is a one way valve for electricity and the regulator is inside the alt. If you suspect a faulty alt or regulator, remove them and have them checked by an autoelectrician. Unless you know what you are doing, DO NOT attempt to disassemble the alt as you can cause catastrophic damage and have to purchase a replacement alt. You may also void any warranty by disassembling the alt.. Undertake these tests and if you have any questions, email me here: swoop@live.com.au
Dave.

Dec 15, 2009 | 1997 Chevrolet Astro

2 Answers

1998 k1500 5.7l 105a alternator. replaced


Now change the sulfated batery for a new one.
Vitally

Sep 09, 2009 | 1998 Chevrolet K1500

2 Answers

Car putting out to high of voltage. New battery in car, now dead.


Usually when the battery light comes on it means there is a problem with the alternator. It means it is putting out less than 12.2-12.5 volts.

Jul 10, 2009 | 2000 Volkswagen Jetta TDI

1 Answer

Alternator not chargeing can i use wd40 to help


First of all.. Check to see if ya have 12 volts going to the back of the alt. If so.. call your parts house and see if it has an external voltage regulator. If so, try a regulator..That was a tricky year when they had either internal and external voltage regulators. otherwise.. get a new alternator. sometimes, the volt gauge will cause a non-charge issue. You can straight wire the gauge to eliminate that.


Mar 08, 2009 | 1989 Chevrolet G30

1 Answer

Charging problem 1991 volvo 240


14.6 means your voltage regulator or diode is suspect Despite having new alternator .Ive cross refrenced your smptoms in the haynes workshop manual and alternator is your only end answer.The haynes test is to start vehicle with multi meter connected across the battery terminals,increase the engine speed until the reading remains steady should be approximately 12 to 13v and no more than 14v.switch on as many accessories as possible(headlights heater blower radio etc)check that the alternator maintains the regulated voltage at around 13 to 14v.If the regulated voltage is not as stated then alternator is to be repaired/replaced.Good luck with it and a happy new year.

Dec 29, 2008 | 1991 Volvo 240

3 Answers

REPLACED THE ALTERNATOR BUT THE BATTERY WILL NOT CHARGE


In this year , there may be an external VOLTAGE
REGULATOR .Instead of an internal regulator inside the alternator. It is usually a square box to the passenger side attached to the fender inside wall. Try replacing this box with a known good one. Or new one if you can get it right away.

Dec 22, 2008 | 1990 Mitsubishi Mighty Max

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