Battery Discharged Overnight?

[Gardd]

The droplets on top of the old battery are definitely acid. This morning I mixed a bit of baking soda with water and put a tiny bit on the affected area of the battery, and it fizzed like hell for a second or two.

I'll put the new battery in this morning (and turn the antitheft system on/off a few times just to be sure), then I'll take the car out on the road then run some errands. I'll test it a few times during the day and I'll also watch for brake lights staying lit when they shouldn't be but like I said I haven't noticed this so far.

If I wanted to test for overcharging - is it simply a matter of putting the multitester on the battery terminals while the car is running, or does the alternator itself have to be tested by a different method?

[Gardd]

I put the new battery in.

The car exhibited the wonky behaviour I've described before including magically unlocking doors. After I turned the anti-theft system on & off a few times and started / restarted the car and left it idling for 5 minutes it settled down and acted normally. It was just fine on the road and was still okay when I got back home.

Took readings a few times & about. Battery charge is normal, alternator reading is normal (measured across the battery) while the car is revved up to 1500, and also running at idle.

I'm still thinking it has something to do with the anti-theft system OR maybe a relay under the dash - power door lock relay maybe? I heard something click right before the doors unlocked themselves.

While out we didn't use the power door locks as a precaution.

Will do some reading about power door lock relays etc. They are way up high under the dash and a real pain to get at.

Will likely do an amp draw test later today too to see if there's a parasitic drain.

[danielsatur]

Found a good DIY video, see GOOGLE ''Youtube auto scotty kilmer battery drain''

[Gardd]

Been a while since I posted about this...

Since installing the new Wal-Mart battery in July the car has been absolutely fine, BUT I left the interior fan relay out and we also haven't used the power door locks all the while.

This morning I had to go on an errand and I thought, what the heck - I'll put the relay in and see what happens.

Car was fine on the way to the store. When I got back in the car there was a beep coming from the dash. So I took the relay back out (and it'll stay out), started the car and the beep stopped. Drove around for a bit and I headed back home.

Get home, turn off the ignition - and those mystery lights on the instrument panel came on just like I saw last June/July. Disconnected the battery; I'll reconnect it later today and I'll watch the car like a hawk again.

So we're back to square one but at least this morning's test tells me the problem is somewhere in the fan circuit. I guess with the cold weather coming I'm just going to make an appointment at our Ford dealer and let them figure it out.

[Scrapper]

Originally Posted by Gardd

Been a while since I posted about this...

Since installing the new Wal-Mart battery in July the car has been absolutely fine, BUT I left the interior fan relay out and we also haven't used the power door locks all the while.

This morning I had to go on an errand and I thought, what the heck - I'll put the relay in and see what happens.

Car was fine on the way to the store. When I got back in the car there was a beep coming from the dash. So I took the relay back out (and it'll stay out), started the car and the beep stopped. Drove around for a bit and I headed back home.

Get home, turn off the ignition - and those mystery lights on the instrument panel came on just like I saw last June/July. Disconnected the battery; I'll reconnect it later today and I'll watch the car like a hawk again.

So we're back to square one but at least this morning's test tells me the problem is somewhere in the fan circuit. I guess with the cold weather coming I'm just going to make an appointment at our Ford dealer and let them figure it out.

when you unhooke neg cable off did it have a high spark or did you notice? if it realy sparked something is on or shorted out bad.

[Gardd]

Originally Posted by Scrapper

when you unhooke neg cable off did it have a high spark or did you notice? if it realy sparked something is on or shorted out bad.

No spark at all when I disconnect or reconnect the negative cable. I just tested it a couple of times and I watched very closely.

[shorod]

Does your Taurus have the automatic climate control or the manual knobs?

-Rod

[Gardd]

Auto. Got an idea?

[shorod]

With the auto climate control, the fan speed is controlled with a solid state motor controller. It's more likely something could fail and cause a current draw with the solid state controller than a simple switch and resistor assembly. You might try unplugging the blower motor controller, reinstall the relay and see if your drain goes away. If so, you've identified the part causing the drain.

[edit] I guess you could go one step further and disconnect the signal wire from the blower motor speed control and confirm that doesn't cause the drain to stop. If that did, then it would suggest the DATC module is calling for the blower motor even when the key is removed from the circuit. One concern I have now that I look at the wiring diagram more closely is the blower motor relay coil only gets power with the key in the Run position.

The source for the switched side of the relay is hot all the time, but if the relay is working, it should be cutting power to the speed control once the key is removed. The next step maybe needs to be confirming that power to terminal 86 of the relay is not present when the key is off, then try swapping the relay with another one. If you're comfortable reading wiring diagrams, send me a private message with the request and an e-mail address for you and I'll send you the 4 PDF pages.

-Rod

[Gardd]

Thanks for the info & offer but that is beyond my comfort level and abilities. I'd rather have a mechanic do it.

I have a day off today so I thought I'd futz with the car.

I reconnected the battery and the two mystery lights on the instrument cluster came on as I expected. I ignored them and got the stupid anti-theft system settled down. Started the car and it ran ok. Stopped the motor, and the lights came on again.

Restarted the motor and um... pounded the dash with my fist all around the heater/radio panel and the glove box.

Stopped the motor and the mystery lights didn't come on. Hmm.

Checked a few times since then and it's still okay.

As the battery was disconnected for two days I'll take it out for a drive on the highway to let the engine relearn its idle & trim etc.