Tip & How-To about Ford F

How to find a short in your car that drains your battery

First; purchase a 12 volt test light from an autoparts store; these look like a screwdriver with a lamp in the handle and, a spike where the screwdriver tip would be; The lamp is attached to a cord that exits the rear of the test light and, terminates in a alligator clip. When the tip of the test light is attached to a 12 volt source; like a positive post of a battery and, the cord of the test light is grounded; like on the negative post of a battery the test light lamp will light, Letting you know that electricity is moving: (doing work) Sometimes electricity will move when it should not, this makes your battery run down, over time. This problem usually can not be found unless you do this: remove the negative battery clamp from the negative battery post then: connect the test light alligator clip to the negative clamp you just removed, and the test light spike to the negative battery post. The lamp should light. This indicates that you have a short to ground: a "leak" that is draining your battery as, if there is no light from the test light you have no problems unless you have a domelight on or, the ignition in the on position for in a "good" car nothing should be lighting the test light bulb.
If you see a bright light you have a big short. If you see a dim light check your alternator for a short through the diodes. With the front door open and, the door button held closed, key off; Look at the lit test light and, start pulling fuses one at a time until the test light goes off; this is the "bad" circuit. Then: replace the "bad" fuse and, just check everything in that circuit one part at a time until the test light goes off again...you have found the problem that causes your battery to run down.

Posted by on

Cars & Trucks Logo

Related Topics:

Related Questions:

2 Answers

battery going dead


Hi. What an annoyance for you. Hello. Drive to any auto parts store and have them check your battery and charging system.
Your battery may need to be replaced. IF they can not find a problem, drive to an autoelectric repair shop where they will have the diagnostic tools to locate the drain on your battery and repair it. J.

Jul 31, 2010 | 1992 Buick LeSabre

2 Answers

only high beam headlights will work. cannot get low beams to work


Hello! Low beam lights are powered by fuse #14 (10A),
And fuse #15 (10A)...If fuse #14 is good check for +12 volts at the fuse...If battery is not present the low beam relay is defective...

Guru..........saailer

Mar 09, 2010 | 1995 Jeep Grand Cherokee

1 Answer

2004 crown vic interior lights stay on


Don't think you have a door ajar switch problem , more then like the lighting control module is the culprit . Does the door ajar light on the instrument cluster stay lit ?
The interior lighting can be separated into two distinct modes of operation: the courtesy lighting and the demand lighting. The lighting control module (LCM) controls all of the interior lighting in the vehicle, as described in the following text.
The front dome lamps, rear reading lamps, and instrument panel courtesy lamps, can be illuminated either by opening any of the vehicle doors (courtesy lamp function) or by depressing the headlamp switch (demand lamp function).
When any door is open, the door ajar switch grounds an input to the LCM which then sends power to the courtesy lamps. The voltage sent to the courtesy lamps gradually increases from 0 volts to 12 volts within 500 ms (± 50 ms), to achieve the theater lighting effect. When the door(s) are closed the door ajar switch(es) break(s) the ground to the LCM input which then gradually reduces the power from 12 volts to 0 volts within 5 seconds. (± .5 second).
When the headlamp switch is depressed it grounds an input to the LCM which in turn sends 12 volts to the front dome lamps, rear reading lamps, and instrument panel courtesy lamps. When the headlamp switch is depressed a second time, it breaks the ground to the LCM input which then ceases to send power to the front dome lamps, rear reading lamps, and instrument panel courtesy lamps.

The battery saver will disrupt power to the courtesy lamps after 10 minutes, the demand lamps after 30 minutes, and the headlamps after 10 minutes. Turning the ignition switch to the RUN or ACC position will terminate the battery saver feature by disabling the interrupt timers and reinstate power to the lamps.
Do you know what DTC'S are ? diagnostic trouble codes !
LCM Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1322 Driver Door Ajar Circuit Short to Ground LCM Go To Pinpoint Test F . B1442 Door Handle Switch Circuit Failure LCM Go To Pinpoint Test G . B1445 Door Handle Switch Circuit Short to Ground LCM Go To Pinpoint Test G . B1563 Door Ajar Circuit Failure LCM Go To Pinpoint Test C . B1566 Door Ajar Circuit Short to Ground LCM Go To Pinpoint Test H . B1685 Lamp Dome Input Circuit Failure LCM Go To Pinpoint Test I . B1687 Lamp Dome Input Circuit Short to Battery LCM Go To Pinpoint Test I . - All Other DTCs LCM REFER to Section 419-10 .

PINPOINT TEST C: THE COURTESY LAMPS STAY ON CONTINUOUSLY CONDITIONS DETAILS/RESULTS/ACTIONS C1 CHECK THE SYSTEM OPERATION Open and close each door, making sure that each door is completely closed.
  • Are the courtesy lamps still illuminated after the 25 second time-out period?
Yes GO to C2 .

No The system is operating correctly. C2 TEST DOME LAMP SWITCH Depress the dome lamp switch.
  • Are the courtesy lamps still illuminated?
Yes DEPRESS the dome lamp switch a second time. GO to C3 .

No The system is operating correctly. C3 CHECK THE LIGHTING CONTROL MODULE
LCM C2145a

  • Are the courtesy lamps still illuminated?
Yes REPAIR circuit 53 (BK/LB). REPEAT the self-test. CLEAR the DTCs.

No INSTALL a new LCM. REFER to Section 419-10 . REPEAT the self-test. CLEAR the DTCs.

Apr 16, 2017 | 2004 Ford Crown Victoria

1 Answer

How do I fix the problem detailed below please


Do you have a 12 volt DC test light? About $5.00-$10.00 at autoparts store or some hardware stores.

Jun 03, 2009 | 2006 Toyota Camry

1 Answer

Power outlets not working


I would spend $5.00 and purchase a 12 volt test light from an autoparts store or hardware store, that way you can test them all, quickly, without pulling them. If there's one thing we've all learned over the years in the autorepair field, is that it's not uncommon, for a circuit to be labeled wrong, or added to another circuit & not labeled at all. A test light will be a welcomed tool in your tool box, and will come in handy more than you think. If it doesn't come with easy, simple instructions, let us know and a 2 minute explanation of where & how to use it will do the trick I'm sure.

Apr 07, 2009 | 2005 Lexus RX330

Not finding what you are looking for?

2,121 people viewed this tip

Ask a Question

Usually answered in minutes!

Top Ford Experts

yadayada
yadayada

Level 3 Expert

75117 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

fordexpert

Level 3 Expert

5474 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Loading...