Question about 2003 Toyota Tundra

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I have a current drain which kills my battery if my 2003 vTundra is not used for a week. We know that if we dissconnect the wire to the fuse box the drain stops. We have pulled all the fuses one at a time, but the dtrain continues. We could not pull a very large fuse, possibly to the alternator, on the left side of the box. The current drain has been since the purchase of the new vehicle, but the dealer said there was no drain. I expect it is more obvious now as the short must be getting worse. I'm on my fourth battery, for after rechargeing enough times the battery fails.

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All vehicles since the 80s have a continuous drain, it keeps the ecm , radio keyless etc, anything that requires memory, although one week is a little short, i would wonder if the battery is not getting a full charge?? like only used on short trips. disconnect the neg terminal and bridge it with a test light, it should glow bright for a few seconds then dim, that is normal , if it stays bright pull fuses one at a time , you should find the circuit that is staying closed

Posted on Nov 11, 2010


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I have a 2001 chevy silverado that must have a short in it as it has killed three batteries . if i take ground wire off overnight and put it back on in the morning the truck will start. If i leave it on...

find a way to detect the current drain, for example a 12 v flashlight bulb, connect that between the + and the wire and it should light if the current is still flowing. Pull each fuse till you see the light bulb go out. The current is pulled by that circuit. When you have identified that circuit, visually inspect that circuit for problems. Examples are: radio wire shaving against bare metal, trailer wire bare. Once you know which circuit drains the battery it should not be to difficult to find the problem.

Dec 05, 2011 | 2001 Chevrolet Silverado

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I have a draw from my battery how can I find it? I have put a test light in between the neg. post and the cable and the light stays on.I have pull all the fuses one at a time and the light dose not go...

Could be a ground problem; I send you a drain test to check it, you will need a digital volt and ohm meter to perform a battery draw test.

WARNING: Do not attempt this test on a lead-acid battery that has recently been recharged. Explosive gases may cause personal injury. Failure to follow these instructions may result in personal injury.

CAUTION: To prevent damage to the meter, do not crank the engine or operate accessories that draw more than 10A.

NOTE: No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

Check for current drains on the battery in excess of 50 milliamps (0.050 amp) with all the electrical accessories off and the vehicle at rest for at least 40 minutes . Current drains can be tested with the following procedure:

Many electronic modules draw 10 mA (0.010 amp) or more continuously.
Use an in-line ammeter between the negative battery post and its respective cable.

Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or interior lamp staying on continually. Other component failures or wiring shorts may be located by selectively pulling fuses to pinpoint the location of the current drain. When the current drain is found, the meter reading will fall to an acceptable level. If the drain is still not located after checking all the fuses, it may be due to the generator.

To accurately test the drain on a battery, an in-line digital ammeter must be used. Use of a test lamp or voltmeter is not an accurate method due to the number of electronic modules.

When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) relearns its fuel trim. The vehicle may need to be driven to relearn the strategy.

Make sure the junction box(es)/fuse panel(s) is accessible without turning on interior or underhood lights. Drive the vehicle at least 5 minutes and over 48 km/h (30 mph) to turn on and activate the vehicle systems.
Allow the vehicle to sit with the key OFF for at least 40 minutes to allow modules to time out/power down.

Connect a fused jumper wire between the negative battery cable and the negative battery post to prevent modules from resetting and to catch capacitive drains.
Disconnect the negative battery cable from the negative battery post without breaking the connection of the jumper wire.

NOTE: It is very important that continuity is not broken between the negative battery post and the negative battery cable when connecting the meter. If this happens, the entire procedure must be repeated. Connect the tester between the negative battery cable and the post. The meter must be capable of reading milliamps and should have a 10 amp capability.

If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be reinstalled to avoid breaking continuity.
Amperage draw will vary from vehicle to vehicle depending on the equipment package. Compare to a similar vehicle for reference.
No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

Remove the jumper wire. If the draw is found to be excessive, remove fuses from the central junction box one at a time and note the current drop. Do not reinstall the fuses until you are finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed and install one fuse, note the amperage draw, then remove the fuse and install the next fuse, etc.

If the current draw is still excessive, remove the fuses from the battery junction box (BJB) one at a time and note the current drop. Do not reinstall the fuses until you have finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed. After removal of all of the fuses, install one fuse, note the amperage draw, then remove the fuse and install the next fuse until each circuit has been tested. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.

Check the wiring schematic in the wiring diagram for any circuits that run from the battery without passing through the junction boxes. This could find in the Service Manual or Haynes books. If the current draw is still excessive, disconnect these circuits until the draw is found. Also disconnect the generator electrical connections if the draw can not be located. The generator may be internally shorted, causing the current drain.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

Nov 18, 2011 | 2004 GMC Envoy

1 Answer

2003 Trail Blazer Problem? Not sure if the issues are related but happened with-in a week of clicking noise coming from the rear panel (3rd row) on the passanger side when I started it clicked about 2-3...

To start, these may or may not be related. First off, the clicking noise from the rear is one of the actuators in the rear HVAC unit. It is clicking either because the door it controls is stuck or the gear is stripped.
What wire did you cut to stop the clicking? And did you tape it up to prevent shorting? If that wire is contacting something, it will cause the battery to drain.
The cars dies when you turn on the AC because you need to clean the throttle body. When you replaced the battery you reset the computer, it now has to relearn to the dirty throttle body.

Jul 21, 2011 | 2003 Chevrolet TrailBlazer

1 Answer

Batery drains overnight

dissconnect one cable from battery. hook a test light between cable end and battery post. ( light on test light will come on if current is drawn). pull out fuses from fuse panel untill light goes out. that circuit is the culprit.

buy a test light at auto parts store. and wrench to dissconedct batt. also buy battery post cleaner.

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I have a 2001 windstar van that died last week.. the mechanic put it on machine and said it was the battery. so tues i went to start it and it was dead again. they said it didn't show alternator killing it...

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Sep 12, 2010 | 2001 Ford Windstar

3 Answers

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Sounds like you have a power drain or short circuit that is killing the battery.

Disconnect the negative battery cable. Put an ammeter between the negative battery terminal and the disconnected cable. Remove fuses one at a time and look for a large drop in current. The fuse with the big drop is on the circuit with the short.

Note that even with the ignition off the radio, the alarm, and the remote entry will pull a few milliamps each. The control module might also draw some power.

After locating the circuit with the problem you need to check wiring and components for shorts.

A service manual (Haynes, Mitchel, Chilton) with wiring diagrams from your local parts store will help after you find the specific circuit.

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BMW X5 Battery Drain.

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Battery/alternator problem

It's hard to know what the previous owner had in mind by installing a kill switch on the fuel pump. Was this to overcome some wiring problem?

You say the battery "suddenly started draining". can you recall anything else that might have happened about that time that might be associated with the "sudden battery drain"?

If you disconnect the ground battery lead can you see any small sparks when you touch the lead to the battery terminal? If you can detect any, this indicates something is drawing current from the battery.
Then remove one fuse at a time and check the presence of sparks again. maybe you might luck out and find which circuit (fuse) is causing the current drain.At least you might be able to isolate the problem

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