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Discussion Starter · #1 ·
got a 1990 taurus, 3.0, for the past 4 mornings, the battery has been completely dead, to the point where i have to leave the jumper cables on it for about 10 minutes before it will start, any ideas why the battery would be draining over night? I thought i saw this before on here..also, the fuel pump kicks on and off by itself sometimes when the car is just sitting in the yard by itself, no keys in it or anything been doing this for over a year now, acts just like someone is turning the key on and off making the fuel pump come on and off, like i said, its been doing that for a long time now, but it never killed the battery before, so i dont think it is causing the battery to go dead..
 

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If you don't have a VOM (mutlimeter), try disconnecting your neg cable from your batt when you park for the night. If the batt is still dead in the morning, get a new batt. If batt is OK, then you need to start looking for the drain.

If you do have a VOM, disconnect the neg cable and use the VOM as an ammeter to check for current flow. Shut off everything, take the key out of the ignition, and close the doors like you would be parking for the night. Set the VOM to measure current (amps). Connect the black lead to your neg batt post. Connect the red lead to the disconnected cable. Should be less than 100mA (0.1 amps). If it's closer to 500ma, leave the VOM connected (you can turn it off), and check the current flow again after an hour or so. Don't know about the Taurus, but my truck draws a a fair amount of current for about 45 minutes after you shut it off.
 

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Check to make sure that your glovebox light goes off and stays off!!

I had this problem with Dad's '87 Ranger. To cut a long story short, jiggling the truck (a bump in the road, to kicking a tire) could make or break the switch for the glovebox light - the door was out of adjustment!

Do you have any service manuals on your car?
 

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Ummmm, try the ignition switch, we had that happen with mom's 89 Sable, and in the end, we were starting to smell a electrical burning smell, but yeah, we were having problems iwth batttery drain, noe since we replaced the switch, no problems, and yes, the ignition switches were fubared from the factory, there was I beleive a recall on them
 

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Discussion Starter · #5 ·
tried disconnecting the battery overnight, went out this afternoon and hooked it up and the car started right up! Its the car draining it overnight somehow, glovebox light doesnt work..i have a voltmeter but it only goes up to 10 amps and the battery is 650 amps..?
 

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Originally posted by 1990@Jun 29 2004, 09:20 PM
tried disconnecting the battery overnight, went out this afternoon and hooked it up and the car started right up! Its the car draining it overnight somehow, glovebox light doesnt work..i have a voltmeter but it only goes up to 10 amps and the battery is 650 amps..?
That's fine, the battery can put out a total of 650 amps, I sure hope you're not drawing 650 amps while the car is just sitting there. If you have a current drain somewhere, it'll probably be just a couple of amps. Most regular items in the car have fuses that are in the 10-20 amp range but you usually don't draw the full amount.

It sounds like you probably have a current drain somewhere. Do as someone else mentioned, disconnect the neg cable and put the VOM between the battery cable to complete the circuit. Once you know how many amps it's drawing, you can pull fuses individually til you see the current draw drop to a more normal level. Then you can trouble shoot that ciruit to see why it's drawing so much current.
 

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Let us know if you find the problem. Sounds like a good one to put under the "Common Problems" area.

-Dan
 

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Originally posted by 1990@Jun 29 2004, 09:20 PM
tried disconnecting the battery overnight, went out this afternoon and hooked it up and the car started right up! Its the car draining it overnight somehow, glovebox light doesnt work..i have a voltmeter but it only goes up to 10 amps and the battery is 650 amps..?
The only time that the battery will deliver this kind of current is when the starter motor is cranking the engine. And it will probably be around 200 to 250 amps, or so. The battery is just rated for 650.

To find your short circuit, you'll need a schematic. Then:

Remove the positive battery cable. Put your meter on the highest Amp range (you may have quite a large short circuit current), and connect your meter IN SERIES with the battery and battery post clamp. What you should see is about 1/3 of an amp draw, which is the power it takes to keep the EEC-IV alive. You will, no doubt, have more.

Now, look at the schematic. Start removing accessory wires and fusible links from the + battery side, one at a time, until the fault goes away and you see just the 330mA (or so) draw of current for the EEC. Another option would be to pull fuses from the fuse block, until the fault current drops off.

Once you've found what circuit it is on, just keep following the wire until you find it. Tedious, but it works.
 

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Discussion Starter · #9 ·
Ill try it, you guys never heard of this before? I thought i read this very same thing on here last year or so and thought someone said it is common, dont remember what the cause was but.. anyway, another thing it has been doing for over a year now..i can be sitting in the yard with the keys in my pocket and every now and then the fuel pump will kick on and off, just like if you were to turn the key in the run position but not crank it, first time i heard it i was going out for work at 5 in the morning and walked by the car and it did this and i thought someone was in the car turning the ignition back and forth, scared the crap out of me, this has never killed the battery before though, but maybe a clue..?
 

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I think a faulty relay (stuck closed) could cause that also.
 

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I'd be calling the ignition switch........

I just have this gut feeling that, that is what it is, with our last experience
 

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Discussion Starter · #13 ·
ok, i did the ampmeter test and pulled out each fuse, didnt change anything, it read a constant 340 mv, the ONLY time it would jump up was when the fuel pump decided to kick on and off, wich happens a lot and it may be whats killing the battery as it is happening more lately, i took the cover off from under the steering column and wiggled all the wiring under it to see if it would make the fuel pump kick on but it didnt, it just does it whenever it wants..the car is also running poorly, it sputters, acts like a 2 stroke weedeater does when you rev it up with the choke on..dont know if this is all linked or what, it started running crappy a while before the dead battery ordeal, but the fuel pump kicking on and off by itself has been going on for over a year, any more ideas guys?
Im desperate and cant afford to take it to a shop..?
 

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You should have a relay that basically turns on the whole pump circuit. I think it would be under the hood. Look for a black box that contains some fuses and relays (cube looking things). On the cover look at the diagram to find which relay is for the fuel pump. Pull that relay out and use your ohmmeter to check for continuity between pin #30 and #87. There should not be any (it should be an open circuit). When the relay is not powered #30 connects to pin #87a. When you power the coil in the relay (pins #85 and #86) it pulls the contacter from 87a to #87, so #30 is now connected to 87.

Sometimes the contacts weld themselves together and it will stay stuck on #87, leaving power to you fuel pump all the time. This is a common problem with relays.
 

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Also, when you have the relay out, check #85 and #86 in the socket (on the car). If you find one of those to have 12V on it, check the other for continuity to ground. If you have both 12v and a ground path, then something in the car is telling the relay to close, so the relay is not the problem.
 

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One thing I should have mentioned, in case you didn't know (and I am not %100 sure but anyway):

This relay is closed whenever your car is trying to maintain fuel pressure (usually when the key is on). The fuel pump will still cycle on and off when the right fuel pressure is reached and then drops off slowly. *edit: The more I think about this, I think I am wrong. It probably does come on and off with the pump. Maybe someone else can confirm one way or the other.

I don't know how often the cycling is when it's normal, but if it cycles too much that could be an indicator of a bad regulator, or leaky injectors maybe.
 

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Discussion Starter · #17 ·
Originally posted by eCarâ„¢@Jul 1 2004, 06:36 PM
You should have a relay that basically turns on the whole pump circuit. I think it would be under the hood. Look for a black box that contains some fuses and relays (cube looking things). On the cover look at the diagram to find which relay is for the fuel pump. Pull that relay out and use your ohmmeter to check for continuity between pin #30 and #87. There should not be any (it should be an open circuit). When the relay is not powered #30 connects to pin #87a. When you power the coil in the relay (pins #85 and #86) it pulls the contacter from 87a to #87, so #30 is now connected to 87.

Sometimes the contacts weld themselves together and it will stay stuck on #87, leaving power to you fuel pump all the time. This is a common problem with relays.
This car doesnt have all that under the hood, its a 1990, all it has is a big black sealed box that sits on top of the radiator that controls all that, i dont think it comes apart or has fuses in it though..?
 

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What does it say on top of that box? Look closer at the sides for the latch to open it. Should have a hinge of sorts on one side, and a latch type deal on the other.
 

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The IRCM (integral relay control module) cannot be opened, it is factory sealed, 340 ma is still a good draw, you said that your car is running rough, what I would do is run your ammeter again, and totally disconnect the connector from the ignition switch, and see what happens there, your fuelpump turning on and off could also be the contacts in the ignition switch.....
 

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Originally posted by firstgen87l@Jul 1 2004, 10:41 PM
The IRCM (integral relay control module) cannot be opened, it is factory sealed, 340 ma is still a good draw, you said that your car is running rough, what I would do is run your ammeter again, and totally disconnect the connector from the ignition switch, and see what happens there, your fuelpump turning on and off could also be the contacts in the ignition switch.....
I had forgotten about those. That's not good. What years did they use those anyway? Pretty crappy that one relay going bad, and you have to replace the whole thing.
 
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