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LWH
New User
Jul 13, 2009, 7:27 AM
Post #1 of 4
(1629 views)
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1988 Chevrolet 1500 Series 1/2 Ton Pick-up 2WD - Battery not getting proper charge from the alternator. The alternator is putting out 14V, but when you test the charging system, it only reads 11V. When you unhook the positive battery cable while the truck is running, sometimes the truck will run, sometimes it will cut off. If you check the voltage when you unhook the positive cable from the battery, it shows 14V.
I have:
tested and replaced alternators
replaced battery
changed starter
traced wires - doesn't seem to be a short
I am wondering if there might be a short in the steering column because the ignition switch has a lot of play in it and when you put on the turn signal, the amp meter fluctuates. This problem goes and comes and sometimes it does fine, while other times the truck idles like it is going to cut off.
Any ideas as to what I can also try?
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Loren Champlain Sr
Veteran
/ Moderator
Jul 13, 2009, 10:23 AM
Post #2 of 4
(1623 views)
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Re: Charging Problem
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LWH; First, you should never disconnect the battery while the engine is running. You can damage the diodes in the alternator by doing so.
The charging voltage should be between 13.6V and 14.6V at apprx. 800-1000 rpm. With the engine off, what is the battery voltage? A fully charged battery should have 13.2V. If the battery is low, it may not be energizing the alternator. Check for a minimum of 12V on the battery terminal connection on the back of the alternator. An alternator can put out voltage, but no or not enough amperage. The voltage output won't be at it's greatest while the alternator is pumping out amperage to charge a low battery. A faulty battery can cause eroneous readings from the alternator. Sooooo....step back, have the battery charged and load tested. At a 40A charge, the battery voltage should not be higher than 14.0V. If it is, it's probably sulphated and needs to be replaced. After the battery is known good, recheck the charging system making sure that you have the needed voltage at the alternator.
I'm sure you've already done so, but make certain that all of your connections are clean and tight. Positive and negative at the battery, starter, and engine block.
Loren
SW Washington
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rodjen700
Novice
Jul 22, 2009, 2:36 AM
Post #3 of 4
(1596 views)
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Re: Charging Problem
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Also bleeding current / ALL OFF / must be <5 mili amperes.
Be sure that ALL is off, even motor hood light, and door light is off also.
Friend M.P.
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