Question about 2008 Ford Ranger

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I have a 2008 Ford Ranger with a good battery, good connections, good alternator, etc. I have been trying to,figure out why the battery is draining overnight only. This happened twice and both times

Please help us to determine what to do to keep the battery from draining. I am currently disconnecting the battery every night.

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Switch your Digital Multi meter to DC AMPs. Amps is usually indicated by an "A" on the Multi meter Switch. AC is usually shown as a "~" symbol and DC shown as a "-" symbol. You usually have to move the multi meter positive lead to a separate socket on the multi meter to check for amps. Sometimes there are 2 sockets, (a high range and a low range). Always test on the highest setting first. For example: High setting on your multi meter may be 10 Amp. Test on the 10 Amp setting first, then if the current drawn is less than your Multi meter's (low setting) move to that setting and keep testing. For example: On my multi meter the low setting is 0.3 Amps. Also indicated as 300mA (mA x 1000 = A).

Remove the battery's positive cable.

Connect the multi meter's positive probe to the battery's positive post while simultaneously holding the negative probe from the multi meter up in the air, to keep it away from anything metallic.

Place the negative probe of the multi meter on the end of the removed positive cable to complete the circuit.

That's right, you're putting a negative on a positive, but its ok, because if the drain is severe enough, you're most likely to blow a fuse or two, which will identify the problem area.

Above I said to remove the positive battery cable because that is the way I do it. You can do the same test with the negative battery cable removed. In fact for you that may be a better way to do the test, because there would be no way for any electrical issues to occur by accidently grounding the negative probe from the multi meter. i hope you understand what I'm saying here.

Posted on Mar 28, 2014


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Posted on Jan 02, 2017

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SOURCE: Charging system

change your battery cables and check all wires on the alternator for loose connections, expecially the grounds.

Posted on Oct 12, 2008

  • 3854 Answers

SOURCE: Current drain

Check the light under the hood, the switch may be bad and the light stay's on all the time and over the visor. Check to make sure the vanity light is off also.  It's just a start and i have known also that the 4X4 actuator will drain too. Keep me posted, be glad to help and it sounds like it's going to be a gremlin to find the battery drain. 

Posted on Jun 23, 2009

  • 1111 Answers

SOURCE: Draining Battery on 1996 Ford Contour

you will need to do a test with a battery light disconnect the negative wire on the battery and connect one end of the test light to the battery and the other to the terminal with everything switched off if the test light is lit you have a draw if it is not lit then it is something else sometimes door switches and glove box switches wear out and need added lift to properly shut the open circuit down

Posted on Aug 26, 2009

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SOURCE: my 1988 ford f350 keeps drawing the battery down

You are going in the right direction. When you have a draw or drain on the battery when not in use the way to find it is as follows. First disconnect the negative cable at the battery. Put a test light between the cable end and the battery post. Have all the doors shut and the key in your pocket. If you have a draw the light will be on. Now that it is on go to the fuse box and pull one fuse at a time and recheck. When the light goes out now you know the circuit to check. The fuse links cover more than one circuit using the fuse method is faster and narrows it down more. Once you know the circuit you can start checking things. Common draws are interior light on and glove box light. Also check the under the hood light the mercury switch in them goes bad alot and they will not light or stay on all of the time. If you think the hood light is a problem slow drop the hood and look under it to see if the light goes out. While checking for the draw if the light works fine just take the bulb out so you don't get false readings. This system to find draws works for I used it for 22 years. Good Luck.

Posted on Sep 27, 2009

  • 2317 Answers

SOURCE: 2000 ford ranger. New battery and brand new

You are correct about that. I would have the new alternator tested, you might have gotten a defective alternator. Whenever I get another alternator, I usually have it tested, I got one from Auto Zone for a Saturn, (which is a pain to change) and had them test it, and low and behold it was defective!! I would check your connectors and if any wires have high resistance.

Posted on May 18, 2010

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