Alternator - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 11 Old 10-31-2017, 03:00 PM Thread Starter
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Alternator

Not sure my alternator is charging. How do I check output on it. It's a 3G on an 87 mustang. The batt and alt are new. Tia

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post #2 of 11 Old 10-31-2017, 06:02 PM
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dc clamp meter is best

or measure batt voltage while turning on loads


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #3 of 11 Old 10-31-2017, 10:43 PM Thread Starter
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I don't have one. All I have is a regular meter. Check voltage at battery with a load. Like headlights on. Voltage should stay fairly steady?
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post #4 of 11 Old 11-01-2017, 03:22 PM
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All loads on, ie blower on. High

Voltage at battery should be 13.5-14.5volts

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #5 of 11 Old 01-18-2018, 10:54 PM
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Also check the fuse able links one might be damaged causing low voltage they should be next to the battery if engine bay hasn't been altered last I remember they are green in color or gray
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post #6 of 11 Old 01-25-2018, 09:30 AM
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Easy. Remove the battery cable with the engine running. The alternator should keep it running.

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post #7 of 11 Old 01-25-2018, 11:15 AM
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Quote:
Originally Posted by turbostang90 View Post
Easy. Remove the battery cable with the engine running. The alternator should keep it running.
Good way to damage electronics.

1988 GT, 57k mi, Orig Owner
ProCharger P600B, FRPP Headers, Flowmaster F2, 3G Alt, Mk8 Fan/DCC, 3.55's, Prog Springs, ST Brace, G/Trac Bar, Subfrms, UCA, LCA, FCA, Tokico 5-ways, C/C Plates, CSA 16x8, Bridgestone RE760 Sport 225/50R16, Megasquirt DIYPNPF60, LC2 WBO2, C&L76mm MAF w/LU47's
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post #8 of 11 Old 01-25-2018, 12:58 PM
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Quote:
Originally Posted by archistudent1 View Post
I don't have one. All I have is a regular meter. Check voltage at battery with a load. Like headlights on. Voltage should stay fairly steady?
Check the voltage across the battery terminals with the engine OFF by setting your volt meter to 20 volt scale. Attach positive lead to positive battery terminal. Attach negative lead to negative battery terminal. Voltage should read around 12.5 volts. Then start the engine, the voltage reading should spike up to 13.8 - 14.2 volts. That indicates the alternator is charging. Turning the headlights and heater ON, the 13.8 - 14.2 volts should still remain the same.
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post #9 of 11 Old 01-25-2018, 10:36 PM
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Good way to damage electronics.
Even better way to cause damage is to connect jumper cables BACKWARDS!
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post #10 of 11 Old 02-12-2018, 11:50 AM
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Quote:
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Good way to damage electronics.
Explain how so?


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post #11 of 11 Old 02-12-2018, 12:12 PM
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Explain how so?
look up alt 'ripple'

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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