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I have a Toyota 1985 mr2 the battery is fully charged but Im only putting out 13.2 volts at 2000 rpm with head lights on it only 125 volts that sound like just batt voltage I might add it has a new al

I have a Toyota 1985 mr2 the battery is fully charged but Im only putting out 13.2 volts at 2000 rpm with head lights on it only 125 volts that sound like just batt voltage I might add it has a new alternater

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Put the blower on high,headlights on high &
leave the doors open & see what you have

12.5 Volts maybe normal for that vehicle, under
that condition @ Idle, not 2,000 rpm

You have to understand your loading the system
with the lights on

Your best to remove every ground wire you can find &
clean the terminals

Remove & check/clean headlight connectors as well

The battery may not be able to take a charge, as well as
you think it can,if it is over 4 or 5 years old,that may be
part of the issue,if there is one

You can go thru 3 alternators to get a decent one

Check Diode Ripple Current,if over .04 Volt leakage, take
that one back & try another

When they rebuild them, they don't replace much

Use the internet to see how to test the alternator on
the vehicle

Posted on Nov 15, 2014


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SOURCE: 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.

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SOURCE: 2000 Windstar no charge light

Check all connections to alt. and battery to make sure they are clean and tight, as it sounds like a loose or dirty connection someplace. Possibly something not tightened completely after battery and alt. replaced? (just enough to get the annoying light to go on occasionally)

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SOURCE: MX5 not charging battery. If i disconnect the

usually cars stall when running and the batterie is removed, indicating a bad alternator.
perhaps your batterie is bad

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SOURCE: im having low idle problems with my 1985 toyota

adjust the carb ,if you do not how to do it then find older mechanic that does

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SOURCE: 2001 Pontiac grand am gt, battery is new,

replace the negative terminal

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2 Answers

How do I check charging system on a 1985 Toyota mr2 ?

Use a multimeter. Check voltage before you start car. Write it down. Start car and check voltage again. It should read 13-14 volts. Turn on headlights and check again.should be the same

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What you have done so far with a test light & volt meter is basically
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1999 Toyota Tacoma battery keeps dying

This is easy to test but you need a multimeter. Connect the multimeter to the battery and run the engine at a fast idle (say 2000 rpm). You should get a voltage reading anywhere from 14 to 15 volts if the battery is fully charged and the alternator is working. If the reading is around 12 volts, then the alternator is not working.

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I have a draw on the battery on my 85 Toyota pickup it kills a fully charged battery in about 2 hours... Ive put a volt tester between the disconnected positive battery cable and the positive battery post...

Try to disconect the battery terminal when the engine runs, if ur engine stop running, it means ur ALTERNATOR is dead!

The voltage output of the alternator should read at 12.5v to 13 volts!

Better go to a pro, to test ur alternator and battery!

May 11, 2011 | 1985 Toyota Pickup

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When head lights are on, gauge drops near red zone goes up a little when rpm rises

Sounds like you have a partial alternator failure probably one bad diode inside. Check charging rate using a volt meter attached to the battery, Charging volts should be around 13,5 with all accessories off and no less than 12.9 with all accessories and lights on. Voltage should never continue to drop but should remain steady or intermittently climb.
Before changing the alternator, be sure the belt is tight and not slipping. If it seems a bit loose, tighten it and re-check charging rate.

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1985 dodge powerwagon, lights went dim driving home now wont start, just replaced battery 6 months ago. starter clicked at first then nothing.

The alternator may not be charging the battery. Jump start it, and use a volt meter at the battery, red lead to positive and black to neg. The meter should read between 13 and almost 15 volts, any lower than 13 volts, the alternator is no good. (this is done with vehicle running).

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87 toyota camry new battery wont keep charge, alternator checks okay, in dash bulb for charge and brake and lights stays illuminated?

Generally if charge light is on, alternator has a bad diode in it. This lets the charged battery lose its power by flowing in the reverse direction. It sounds as the alt., is either not connected right or is swtill bad

Jan 18, 2010 | 1995 Toyota Camry

1 Answer

I have a volt/ohm meter and need to check the alternator output voltage on a 1988 honda civic. How do I do this

put the meter in dc the range of at least 20 volts dc
.. put the red lead in the positive "+" terminal of the battery and the black lead to the negative "-" terminal of the battery.
start the engine and observe the voltage readings

if the alternator is charging fine, the reading should be 13.8 v dc or nearer...

turn on the ac, it should go down to at least 13 volts...
turn the head lights on, and you should have at least 12.5 volts....

if lower than the readings, try to rev the engine at 2000 rpm and observe again the readings,

if still low, you may have a faulty alternator.

i hope i was able to solve ur problem...

pls rate me



Jul 26, 2008 | Honda Civic Cars & Trucks

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