Parasitic Drain
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Laughing Gas
Joined: Jul 2003
Posts: 765
Likes: 13
From: Edmond, OK
Parasitic Drain
I've done a little research on here and a couple other places.
Seems as though the alternator (diode) or the voltage regulator may be bad.
I'm not great with electrical, luckily in my 50 years on this ball, I haven't had that many problems. If I pull the alternator to have it tested, will it confirm the diode being good/bad?
How do I test the regulator?
Seems as though the alternator (diode) or the voltage regulator may be bad.
I'm not great with electrical, luckily in my 50 years on this ball, I haven't had that many problems. If I pull the alternator to have it tested, will it confirm the diode being good/bad?
How do I test the regulator?
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Regulator test:
Attach your DVOM to the battery and note the charging voltage. Should be ~ 14.4 VDC. No?
With the vehicle running, pull the plug on the regulator and jump the (+) BATT to the F (FIELD) on the alternator. This will 'excite' the alternator causing the voltage to go up. If it does, the regulator went south....and/or mebbe check the wiring. If the voltage doesn't go up, the alternator has problems...one or more diodes are pooched.
Attach your DVOM to the battery and note the charging voltage. Should be ~ 14.4 VDC. No?
With the vehicle running, pull the plug on the regulator and jump the (+) BATT to the F (FIELD) on the alternator. This will 'excite' the alternator causing the voltage to go up. If it does, the regulator went south....and/or mebbe check the wiring. If the voltage doesn't go up, the alternator has problems...one or more diodes are pooched.
Laughing Gas
Joined: Jun 2016
Posts: 855
Likes: 56
From: Des Moines, Washington
If you have a test light or make one from a small 12 volt lamp, you can put it in series with one of the battery cables. Just disconnect a cable at the battery, clip one end of the light the the cable and the other to the battery terminal.
It will light up as long as the parasitic drain is active. Disconnect wires from the alternator and regulator, one at a time if you can until the light goes out. If it doesn't go out, pull fuses. If it's still lit, start taking every plug you find apart.
If it doesn't light up in the first place,find a smaller lamp or use a DVM set to D.C. current. The reason I would use a lamp over a DVM is that the lamp is current limiting but the DVM is a dead short and if connected incorrectly will at minimum blow a fuse and worst case is a fire.
Having said all this, you may want to make sure your brake light switch is working. Mine has slipped and caused the lights to stay on. Hard to catch if you can't see the rear end of your truck from the house!
Michael
It will light up as long as the parasitic drain is active. Disconnect wires from the alternator and regulator, one at a time if you can until the light goes out. If it doesn't go out, pull fuses. If it's still lit, start taking every plug you find apart.
If it doesn't light up in the first place,find a smaller lamp or use a DVM set to D.C. current. The reason I would use a lamp over a DVM is that the lamp is current limiting but the DVM is a dead short and if connected incorrectly will at minimum blow a fuse and worst case is a fire.
Having said all this, you may want to make sure your brake light switch is working. Mine has slipped and caused the lights to stay on. Hard to catch if you can't see the rear end of your truck from the house!
Michael
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Lasermike has some good tests there to diagnose a drain.
Thread Starter
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Laughing Gas
Joined: Jul 2003
Posts: 765
Likes: 13
From: Edmond, OK
Last night I took the regulator off and looked at the terminals, they looked almost new. Took the cover off to look inside, also looked new. Tonight I pulled the alternator to take to Napa in the morning to test. I put the battery on the charger at low voltage for an hour, now its on a tender, will check it in the morning.
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Laughing Gas
Joined: Jul 2003
Posts: 765
Likes: 13
From: Edmond, OK
Regulator test:
Attach your DVOM to the battery and note the charging voltage. Should be ~ 14.4 VDC. No?
With the vehicle running, pull the plug on the regulator and jump the (+) BATT to the F (FIELD) on the alternator. This will 'excite' the alternator causing the voltage to go up. If it does, the regulator went south....and/or mebbe check the wiring. If the voltage doesn't go up, the alternator has problems...one or more diodes are pooched.
Attach your DVOM to the battery and note the charging voltage. Should be ~ 14.4 VDC. No?
With the vehicle running, pull the plug on the regulator and jump the (+) BATT to the F (FIELD) on the alternator. This will 'excite' the alternator causing the voltage to go up. If it does, the regulator went south....and/or mebbe check the wiring. If the voltage doesn't go up, the alternator has problems...one or more diodes are pooched.
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Thread Starter
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Laughing Gas
Joined: Jul 2003
Posts: 765
Likes: 13
From: Edmond, OK
If you have a test light or make one from a small 12 volt lamp, you can put it in series with one of the battery cables. Just disconnect a cable at the battery, clip one end of the light the the cable and the other to the battery terminal.
It will light up as long as the parasitic drain is active. Disconnect wires from the alternator and regulator, one at a time if you can until the light goes out. If it doesn't go out, pull fuses. If it's still lit, start taking every plug you find apart.
If it doesn't light up in the first place,find a smaller lamp or use a DVM set to D.C. current. The reason I would use a lamp over a DVM is that the lamp is current limiting but the DVM is a dead short and if connected incorrectly will at minimum blow a fuse and worst case is a fire.
Having said all this, you may want to make sure your brake light switch is working. Mine has slipped and caused the lights to stay on. Hard to catch if you can't see the rear end of your truck from the house!
Michael
It will light up as long as the parasitic drain is active. Disconnect wires from the alternator and regulator, one at a time if you can until the light goes out. If it doesn't go out, pull fuses. If it's still lit, start taking every plug you find apart.
If it doesn't light up in the first place,find a smaller lamp or use a DVM set to D.C. current. The reason I would use a lamp over a DVM is that the lamp is current limiting but the DVM is a dead short and if connected incorrectly will at minimum blow a fuse and worst case is a fire.
Having said all this, you may want to make sure your brake light switch is working. Mine has slipped and caused the lights to stay on. Hard to catch if you can't see the rear end of your truck from the house!
Michael
Thread Starter
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Laughing Gas
Joined: Jul 2003
Posts: 765
Likes: 13
From: Edmond, OK
alternator tested bad. it was charging though.
I got a new one, but its not clocked the same, make any difference?
sorta bummed, was hoping to get an old style case, not the newer one I got.
I got a new one, but its not clocked the same, make any difference?
sorta bummed, was hoping to get an old style case, not the newer one I got.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Yes, it makes a difference in the way the wires are hooked up - length of 'em and how they snake through to attach. You could try it w/out clocking it....
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