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Measuring Amperage Drain


Old 08-17-2000, 09:37 PM
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Question Measuring Amperage Drain

Does anyone know how to measure the amp drain coming off the battery with a standard multimeter? I have a 97 F150 XLT 4.6. When I turn the truck off and let all the lights go out the truck is still drawing approx. 4 amps from the battery. This was confirmed with a test on the battery/alternator at auto zone using their tester which test for that. I would love to test this myself at home and try to fix it.Any help would be appreciated.
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Old 08-17-2000, 11:17 PM
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Join Date: Apr 2000
Location: Wichita, Ks.
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I have a tool sold by SNAP ON that connects between the battery neg. and the removed neg. cable which will allow you to hook up an amp meter and turn a **** which allows the current to then pass thru the meter. Then you can pull fuses until the demon is found.


2000 XLT Bright red, Flareside,extended cab,sport,5.4,bedrug,Extang tonneau.
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Old 08-18-2000, 12:50 AM
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Here's a pic how to. One important thing is when you hook up the ampmeter. DO NOT turn on the ignition key (on). Most meters will only handle 10-20 amps. Turning the ignition may/will exceed that, and will blow your meter's fuse.
Easy way is just to unhook the positive battery terminal and hook the ampmeter in between the "+" post and power cable. A 4 amperage draw does seem alittle high, but in todays electronics it is possible. I will be installing a bigger battery this weekend, so I'll give it a try and give you a reply on what I get.

1999 F250 LD S/C XLT 4x4
5.4L, 3.73, 4R100 trans.
Flowmaster 40 series, K&N, Poweraid, Superchip, Rancho RSX shocks, Stull billet grille, 2-PIAA Pro80XT's (120W), 2-KC Daylighters (150W)
265/70 R17 BFG AT KO's on 17x8 American Racing Atlas rims
Kenwood 7000 CD, Alpine 3342 Signal Processor, Alpine MRV-F353 5Ch. Amp, Pioneer TS-A6865 3-way speakers, Lightning Audio 1 Farad Capacitor, RS10A Bazooka Bass Tube. CompuStar alarm/autostart.

[This message has been edited by Jupiterak (edited 08-18-2000).]
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Old 08-18-2000, 07:57 AM
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Location: South of the Red River
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You can not connect a standard multimeter in series like the ampmeter unless your multimter is rated as an ampmeter. You will fry the unit (and maybe other things as well). Remember that measuring voltage is not the same as handling a current.

2000 F-150 XLT Sport, Silver 4-door Supercab StyleSide
Short Bed (Only way to fit in the garage)
17" Sport Wheels with BFG tires, 3.55 R, 4.6l V8, Auto (First one in 20 years)
In-Dash Single CD Player, 60/40 Split bench dark graphite

Mods So Far
Fumoto Drain Valve, K&N Filter, Gatorback Spray-In Bedliner,
Llumar ProShield Window Tint, WMS Velocity Tube

Future Plans
Superchip, Upgraded Speakers/Stereo
FlowMaster Exhaust, Nerf Bars

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Old 08-18-2000, 08:44 AM
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If you want to test the draw with everything off, like it would be in normal use, you may need to sequence it.
Your DVM ammeter probably won't have enough range to handle ignition ON (fuel pump draw mainly), so will have to slip connections.

Pop off neg terminal cable.
Put cable back on, but don't tighten anything. This was all just to be able to get it off easy later.
Turn key to ON.
Turn off.
Wait for controller to time out the lights (underhood light is easy).
Put ammeter neg lead on neg center post of battery.
Pos lead of ammeter to neg cable. Ammeter will read zero, since its shorted, that's OK here.
Now, (more hands helps!), slip the neg cable off the battery post without breaking the ammeter connections.
Ammeter will now read your timed-out OFF draw.
Don't turn it back to ignition ON without putting neg cable back on battery post, or disconnecting ammeter, or you could blow your DVM's ammeter (or its internal fuse).

4 amp draw in sleep mode is too high. But be sure it went into sleep mode. Wait.
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Old 08-18-2000, 07:18 PM
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Thanks for the help from all. I will be attempting to find the problem this weekend. Hopefully..
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Old 05-09-2001, 06:15 PM
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Location: Anchorage, AK USA
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I too have a '97 F-150 XLT 4.6L. I'm trying to diagnos mine as well. Did you by chance find out what the amp draw should be? Mine is currently between .20 and .39 in sleep mode...What did yours show?

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Old 05-09-2001, 06:19 PM
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Location: Little Elm, Texas USA
Posts: 207

Be careful with only takes less than 1 amp to kill you.

1999 F-150 Sport Supercab
Bright Red 4.6L Auto
Billet Grill, Billet Ant, Clear Corners, Sony CD Player, Pioneers in all doors, Kicker 100si Amp, MTX preformed underseat box. Fiberglass Bed Cover
2000 Expy Sport
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Clear Corners, Alpine CD Player, Punch 150 Amp, JL Audio preformed sub box in rear panel.
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