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ok 96 t-bird 4.6 BRAND new alternator like not even a day old as of this posting issue was with ac on and lights and even turn signals i would drop volts bad, if the lights and ac were on i would drop all volts to the point the ac would shut off... tonight threw on a new alternator still dropping volts bad with ac and headlights on its not shutting off anymore but i havent ran it long either.... so what could be causing such a huge draw????? and the battery is in perfect shape too. all wires are good all connections are good......im lost....
 

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Discussion Starter #3
below 11 dropped to 9.8 when stuff shut off. wires arent corroded unles its in a place where i cant see we striped the the wire looms and nothing looked bad at all and we have solid connections everywhere
 

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Some ideas..............

Are you measuring volts at the battery with a multi-meter or are you watching your volts gauge on the dash? I would not rely on the gauge for accuracy if you are.

Check the 175 Amp fuse for corrosion/damage/loose condition. It's located on the side of the fuse box in the engine compartment. In that same fuse box check to see if 15 Amp fuse 11STD is blown.

Might seem an obvious question but whats your belt tension like? Take the belt off and give the accessory pullys a spin, are any stiff or ceased?

You've made it clear that you checked connections and say they're solid but respectfully I would have second look, particularly at your battery ground at the frame. Disconnect it and make sure there's zero corrosion and that there's metal on metal contact. Same goes for the battery post and all other connections related to the battery/alternator wiring. The four wire connector at the alternator are sometimes known to burn and distort. There is an engine block ground located close to the starter, same advice as before. Its hard to gauge everybody's experience/definition of a solid connection, so apologies in advance.

Hope this helps
Chris..............
 

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Discussion Starter #5
thanks chris i have double checked all connections the 175a fusable link was replaced about 6 minutes after the alternator i have not checked the tensioner pulley and all others though.. i will do that later.
 

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I have a similar problem..

when my car warms up the voltage on the gauge go's from the middle down to a little over a 1/4
with a/c and headlights on.

Battery is good and post connections are good plus I added a ground from the battery post to the alternator bracket with no luck..
 

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Discussion Starter #8
checked pulleys they seem fine but meter is still reading 11.2 v loaded (lights and ac on) and 12.5 - 13.2 with no load (just engine runing) and its being tested with a multimeter and it was tested at parts store both read the same. im am at a loss i can figure it out. im gonna shoot it!
 

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Gonna have to dig deeper.....................

Can appreciate and hear your frustration. If you're still willing I've a few more ideas?

With your multimeter try a voltage drop test from the block to the negative battery post (connector attached.) Touch/attach the positive lead of your multimeter to the Alternator frame and the negative lead to negative post of the battery post (not the connector.) With the engine running observe the voltage on your meter.

Anything over 0.100 volts (100.0 mV [millivolts]) is unacceptable and points to a bad ground, or in your case a bad ground wire (internal corrosion/breakage etc) to the block and/or frame. I would even consider 0.050 volts (050.0 mV) questionable.

voltage drop test is just another way of measuring resistance in a circuit.

Similar checks can be made across the positive lead, wires and connectors. I can give you the procedure and values if the voltage drop test for the block ground checks ok.

One further question. Are you finding the battery dead or low, overnight or after a day or so?

Hope this helps.
 

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Discussion Starter #10
will try the drop test my battery died one time when this all started happening hasnt hurt the battery since the new alternator.
 

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Just wondering (sorry if I missed it), does your battery light turn on when this happens? If you but the car in the run position, does the battery light turn on then? If you have no battery light, then you will have no charging.

Stephen
 

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I had about the same issues, but a new alternator fixed it. You might want the check the alt plug and the power wire, or you might just try changing that wire out (the one going from the alt to the power distro box)
 

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voltage drop comparison values for you...............

Hope there's been progress.

Thought I'd post values measured on my T-Bird based on voltage drop for a charging circuit. Rather than type out the procedure I've copied & pasted the procedure I use from the - Carley Library of Automotive Repair Articles - at http://www.aa1car.com/library/voltage_drop_testing.htm

My CHARGING system's values for your comparison are:

Alternator + to Battery +
2000 RPM No Load 0.049/0.055
2000 RPM --- Load 0.148/0.151

Hot Idle No Load 0.037
Hot Idle --- Load 0.078

Alternator frame (-) to Battery -
2000 RPM No Load 0.027
2000 RPM --- Load 0.150

Hot Idle No Load 0.025
Hot Idle --- Load 0.110

Here's the procedure.

CHECKING THE CHARGING CIRCUIT

To check alternator connections on the positive side for excessive resistance:

A. Set meter on 2 volt DC scale.
B. Connect the meter positive lead to the alternator output stud (B+ terminal).
C. Connect the meter negative lead to the positive (+) battery post.
D. With the engine running at 1,800 to 2,000 rpm with all lights and accessories
on (except the rear electric defroster), check the voltage drop reading. It should
be 0.5 volts or less. If higher, the connections between the alternator output stud
and battery need to be cleaned. Also, look for loose connections or undersized cables.

To check the alternator connections on the negative side for excessive resistance:

A. Set meter on 2 volt DC scale.
B. Connect meter negative lead to alternator case.
C. Connect meter positive lead to battery negative (-) post.
D. With engine running at 1,800 to 2,000 rpm with all lights and accessories on
(except rear defogger), check the voltage drop reading. On the negative side, it
should be 0.2 volts or less. If excessive, the connections need cleaning or the
negative cable needs to be replaced. Some alternators are mounted in rubber
bushings and have a separate ground strap. If so equipped, be sure to check
the voltage drop across this strap, too.

Hope this helps.

Chris.........
 

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you have a wire coming from your ignition switch that gives the alternators regulator a + signal to turn it on, if that wire is pinched or corroded it will have resistance in it and cause the alternator to put out less power... had this happen on a chevy beretta

also check the alternator pulley... seen this once on a audi, the alternator pulley was slipping and it would drain the battery. It was funny, with the engine running it would drain the battery all the way down and almost stall the car, yet as soon as you took the battery terminal off the car would roar back to life and the lights and all would be super bright.
 
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