Voltage drops significantly when breaks applied.
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Novice
Joined: Sep 2020
Posts: 21
Likes: 6
From: Fredericksburg, VA
voltage regulator tested bad, as well as the batteries. Granted, the second one may have been unwarranted. Getting ready to do some testing now.
Thread Starter
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Novice
Joined: Sep 2020
Posts: 21
Likes: 6
From: Fredericksburg, VA
voltage regulator tested bad, as well as the batteries. Granted, the second one may have been unwarranted. Getting ready to do some testing now.
Thread Starter
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Novice
Joined: Sep 2020
Posts: 21
Likes: 6
From: Fredericksburg, VA
First off, I appreciate all the help. Im usually good with the mechanics, but electrical drives me batty.
ok.. load tested battery (I happen to work at AutoZone). Tested good, 11.79 volts 0% charge.
with engine running, 14.05 V @3600 rpm.
I couldnt get any ready on my meter across the regulator pins. It would show a number then drop to zero.
positive probe on regulator pin and black on negative batt post started about .55 volts and dropping as I watched.
stator check, I believe is fine.. aprox 19.5 vac @1k rpm and 39.5 to 40.1 vac @2k rpm.
ok.. load tested battery (I happen to work at AutoZone). Tested good, 11.79 volts 0% charge.
with engine running, 14.05 V @3600 rpm.
I couldnt get any ready on my meter across the regulator pins. It would show a number then drop to zero.
positive probe on regulator pin and black on negative batt post started about .55 volts and dropping as I watched.
stator check, I believe is fine.. aprox 19.5 vac @1k rpm and 39.5 to 40.1 vac @2k rpm.
Seasoned HDF Member
Joined: May 2008
Posts: 21,173
Likes: 12,740
From: South Carolina
Please clarify your original post:
You say the voltage drops significantly, have you verified this with a voltmeter (not the dash voltmeter)?
Connect a voltmeter to the battery posts and read the voltage with the engine running, spotlights on.
Does it read the same as the voltmeter in the dash?
Does the turn signal cause the voltmeter to vary like the dash voltmeter?
If you have to charge the battery after a few days, either the battery is bad, or you have a parasitic drain.
Disconnect the negative battery cable from the battery post.
Set your meter to read milliamps.
Touch one probe to the negative battery post.
Touch the other probe to the disconnected end of the negative cable.
What is the milliamp reading?
Wiring Diagrams and Troubleshooting
You say the voltage drops significantly, have you verified this with a voltmeter (not the dash voltmeter)?
Connect a voltmeter to the battery posts and read the voltage with the engine running, spotlights on.
Does it read the same as the voltmeter in the dash?
Does the turn signal cause the voltmeter to vary like the dash voltmeter?
If you have to charge the battery after a few days, either the battery is bad, or you have a parasitic drain.
Disconnect the negative battery cable from the battery post.
Set your meter to read milliamps.
Touch one probe to the negative battery post.
Touch the other probe to the disconnected end of the negative cable.
What is the milliamp reading?
Wiring Diagrams and Troubleshooting
Last edited by Dan89FLSTC; Mar 16, 2022 at 12:42 PM.
Thread Starter
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Novice
Joined: Sep 2020
Posts: 21
Likes: 6
From: Fredericksburg, VA
Ok. Sorry I thought I had other info there but I didnt. (And will do the parasitic test when I can.
its not just the volt meter on the dash. When I hit the brakes the radio will stop working for a second, the lights dim, at certain points the blinkers wont work.
Ran out of time during lunch so will do the other tests suggested when I can.
its not just the volt meter on the dash. When I hit the brakes the radio will stop working for a second, the lights dim, at certain points the blinkers wont work.
Ran out of time during lunch so will do the other tests suggested when I can.
Thread Starter
|
Novice
Joined: Sep 2020
Posts: 21
Likes: 6
From: Fredericksburg, VA
If you have to charge the battery after a few days, either the battery is bad, or you have a parasitic drain.
Disconnect the negative battery cable from the battery post.
Set your meter to read milliamps.
Touch one probe to the negative battery post.
Touch the other probe to the disconnected end of the negative cable.
What is the milliamp reading?
Wiring Diagrams and Troubleshooting
Disconnect the negative battery cable from the battery post.
Set your meter to read milliamps.
Touch one probe to the negative battery post.
Touch the other probe to the disconnected end of the negative cable.
What is the milliamp reading?
Wiring Diagrams and Troubleshooting
Seasoned HDF Member
Joined: Feb 2007
Posts: 6,086
Likes: 1,128
From:
What does the wire loom under rear fender look like?
Reason:
Perhaps the wire loom is damaged in some way due to wire scrub from tire and when pressing the brake it causes a another circuit to energize.
Reason:
Perhaps the wire loom is damaged in some way due to wire scrub from tire and when pressing the brake it causes a another circuit to energize.
Seasoned HDF Member
Joined: May 2008
Posts: 21,173
Likes: 12,740
From: South Carolina
Something always draws power, as long as it is within service manual limits it is ok.
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