Posted on 03/22/2015 3:30:31 PM PDT by waterhill
I am trying to help a friend with her truck. It is draining the battery. It is a 98 ford, which I detest (loyal Gmc owner). My meter is reading 12.76 V on the battery terminals. When I hook up the posi and jump my meter from the neg term to the neg cable, I get -12.76. This truck is sitting on top of a water puddle (we are wet out here this spring) and I refuse to crawl under it.
I know there are a lot of people here that have this, I just get creeped out by fords and lose my mind around them.
Help!!!
Push it to a dry area...
Break Switch sticking causing the break lights to stay on after exiting the vehicle?
That was my next guess but figured that year model doesn’t have a glove box light.
Modern cars and trucks have a parasitic power drain - various on board components constantly draw power even if the car/truck isn’t running.
Get a battery charger to maintain the battery and always keep it hooked up at home.
Word.
My son's F250 Powerstroke did this. It would start cranking in the middle of the night with no one around. Radio, heater blower and cab lights would come on by themselves as well. Finally put on an RV ground cable cut-off relay to stop the demons.
Got to wait 'til he comes home to do a proper fix.
Fords tend to have odd electrical and computer problems as they age and tend to be tricky to track down. Unlike GM products that loose wheels or the fuel pump goes out leaving you suddenly stranded. GM issues tend to be kind of obvious (and sometimes dangerous).
I’d see about an auto electrical specialist. We have one nearby but if it is wet where you are it would probably be a long drive - we haven’t had rain in weeks.
I can think of more creepy things to worry about than a make of car....
You're no dummy. Absent alot of diagnostic tools, that's the best and fastest way to find the problem.
You may be dealing with leakage from the battery cables. Try replacing them.
Is there an aftermarket trailer hitch with a connector for the trailer lights? Could be a partial short there. A dead short would likely blow a fuse. A switch or a light not turning off completely would cause a slow drain. Any light left on would be easy enough to find, and a stuck lighter would probably burn up before it drained the battery. I agree with the suggestion of reading the battery voltage across the terminals with the engine running. Any less than 13 volts is not charging the battery. Since it and the alternator are new, I’d start looking at the regulator.
+1 for the windshield leaking on the gem. Seen it a few times.
I stand corrected.
I had that once a while ago - and I did what was suggested here. Put an ammeter in series with battery and pulled out fuses. Eventually, when I pulled out the fuse that contained the clock (mechanical clock, back then) the drain was gone. Then I disconnected the clock and put the fuse back. Drain was still gone. Never had a problem again, nor a clock again, for that matter.
In the case of newer cars, if you disconnect the battery terminals, the main computer will not give a green light if you get it emission-tested, until it completes the prescribed driving cycle needed for it to reset. Eventually, during normal driving, you’ll get that task done by default. If you don’t have to get the vehicle emissions-tested then it’s not an issue. If you do, then make sure you are still a few months away from that test before disconnecting the battery.
Also, there are devices made just for that - they plug into the lighter socket, have a small battery, and keep the computer alive while the battery is disconnected, such as these:
Just be sure to read the instructions - you may have to apply external power to the device while the battery is being disconnected, depending on the type you get.
If it’s a 98 F-150, I had the same issue. I think it was water splash issue - water would splash up and get something wet which kept drawing power after the truck was shut off. My solution was to install a kill switch on the battery, so when it was wet I would disconnect the battery while the truck was parked. Didn’t fix the problem but it worked around it.
Or pop that distributor cap and have some Norman ‘tard wee-wee on the rotor while you crank it to, uh, check the, hmmm, resistance.
Yeah, that’ll make his putter stand up, yeehaaaaaaa!
Instead of spending $800 to rewire, I would have wired in a SPST cutoff switch to the battery.
Not sure if I understand what you are doing here.
Does this mean you have the positive and negative terminals connected to the battery and your meter setup is Black meter lead on Neg. terminal of battery and red meter lead on Negative cable where it meets engine ground??? That would read -12.76 Volts if your ground connection was open (bad ground cable or connection at battery or engine connection).
I had this problem on a ford many years ago where the culprit was the short red cable from Battery to starter solenoid on fire wall. Car acted like the battery couldn't start car but when I put the meter across that cable I measured 9 volts when trying to crank the car over.Only 3-4 volts was getting to Starter.That short cable was bad
Is battery really draining down or are the symptoms a no crank condition?
Need several more points of info to really help
But I will give ya a few things to try.
If the battery is really being drained, Then the Ammeter/testlight in series with power cable and pulling fuses will help you find which circuit is causing the drain. Then trace wires looking for shorts or rub marks.
If the symptom is a no crank condition even though there is a new battery, Then you may have bad connection/cable in the ground or starter cable.
Starter circuit uses heavy duty wires because the starter pulls huge amounts of current when engine cranks and any resistance in line will cause a voltage drop and the starter won't get the voltage/amperage it needs to crank the engine.Circuit path is Positive battery terminal thru large red cable to starter motor, thru starter case to engine ground and back to battery thru Black cable.
You can put volt meter across each section of circuit and look for voltage drops.
1.) Meter across battery terminals,try to start truck. If voltage drops way down and stays down while trying to crank, Battery isn't doing it's job.
2.)Meter from Pos battery terminal to starter connection. try to start truck.If you see a large voltage drop,Then you have a bad connection or cable.
3.)Meter from Engine block to neg battery terminal,try to start truck,If you see a large voltage drop,Then you have a bad ground connection or neg battery cable/connection.
4.)stuck or bad starter can also pull battery voltage down while trying to crank it over
If you use a typical voltmeter/ammeter to do your trouble shooting , most of them can't handle large currents. 300 mA or 10 amp settings. If you have it inline with red battery cable and try to start the truck it will blow the fuse in the meter.
Not sure about how the negative reading is happening - sounds like a user issue w/o clarification. If the battery is older, replace it - voltage doesn’t always mean current is available. Many modern car electrical systems will give weird readings when the battery gets weak. If the car can be started/jump started, and seems to run OK, then I would assume the battery is low on vitamin Ampere.
Brand doesn’t matter, they all pretty much operate the same way. I have a 2004 Expedition that had this issue. Turns out that the rear windshield wiper unit was not returning to the “park” mode because the unit was broken. By not being in park mode, it was running power to the unit to try to get it to park. This killed the battery overnight. Had to replace the unit. Once that was done, no more problems. Son is driving it, truck has 180,000 on it, drives like new.
Did you discover what the problem was?
Shorted fuel pump relay running pump with ignition off? Bad ignition switch staying “hot” in the off position?
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