battery drain

[Loren Smith]

I have a 2001 Sport Trac that has a battery drain issue. New battery 11 months ago. If truck sits for just a few days, the battery is dead. When disconnecting the battery cables, I see a spark. I realize the PCM introduces a constant draw on the battery but I believe it is very minimal, how much draw should I expect to see?

 

[CDW6212R]

Look for any other odd electrical symptoms, for example do the fog lights stay on with the engine off. It may be a wiring issue from someone working on something, or as simple as an old sticking relay. My 98 Mountaineer did that many years ago, the fog light relay was leaving the fog lights on. I threw that relay away and installed a spare one.

If nothing is obvious, then begin to remove fuses one at a time, that can take a lot of time, but it will narrow it down.

 

[Loren Smith]

Look for any other odd electrical symptoms, for example do the fog lights stay on with the engine off. It may be a wiring issue from someone working on something, or as simple as an old sticking relay. My 98 Mountaineer did that many years ago, the fog light relay was leaving the fog lights on. I threw that relay away and installed a spare one.

If nothing is obvious, then begin to remove fuses one at a time, that can take a lot of time, but it will narrow it down.

I see no other symptoms. Using my meter, I'm seeing about 200 ma of draw. Under the hood where the relays and some fuses are, if I pull the relay marked "main fuse panel", the draw drops to zero. I think I'm ready to go inside and start pulling fuses. Am i on the right track?

 

[CDW6212R]

Yes exactly, with a good meter to monitor it, you should be able to track it down easily. Finding it and fixing it will be different, hopefully it's just something simple like an old relay.

 

[Loren Smith]

Yes exactly, with a good meter to monitor it, you should be able to track it down easily. Finding it and fixing it will be different, hopefully it's just something simple like an old relay.

OK Great. Next question...I'm working on a 2001 Ford Explorer Sport Trac...where is the door switch that turns the interior lights on and off? I must be brain dead....can't find it.

 

[Mr. Alligator]

The door switches are inside the door… removable switches attached to the door lock assembly.


Good luck.

 

[CDW6212R]

Ditto, they began putting them in the door latches in 1995 Explorers. Now try to find the switch to turn the lights on manually, or off. That's the thumb wheel right next to the headlight switch. Push that all the way up, or down, I love that feature.

 

[NIP]

Yes exactly, with a good meter to monitor it, you should be able to track it down easily. Finding it and fixing it will be different, hopefully it's just something simple like an old relay.

I had a similar issue. Replaced all relays and the problem went away and hasn't returned. Kind of a blunt solution but this took me approx. 10 minutes. I saved the relays and ordered a relais testkit to check them later. But for now the car is fixed.
Had something like this with two of my Crown Vics. Both times the A/C clutch relay was stuck and was responsible for the battery drain. Shop searched and charged me for three hours to find it and replace the $5 thing.

 

[Loren Smith]

The door switches are inside the door… removable switches attached to the door lock assembly.


Good luck.

thanks!!! now i can go to work.

 

[CDW6212R]

The relays are getting harder to find, and more expensive. I've collected about 5-10 of them, but each car needs I'd bet 20 or so. At $10-$20 each for OEM, that adds up fast.

 

[NIP]

The relays are getting harder to find, and more expensive. I've collected about 5-10 of them, but each car needs I'd bet 20 or so. At $10-$20 each for OEM, that adds up fast.

Found them on Amazon after a long time of Currently Unavailable messages. I think 5 pieces for $20.

 

[Loren Smith]

Found them on Amazon after a long time of Currently Unavailable messages. I think 5 pieces at $20.

OK I think I'm making headway. Meter showing 200ma draw with everything off and door switch jumpered (truck thinks door is closed). I pulled fuse 26 and the draw dropped to 50ma. Fuse 26 controls "interior lamp relay and the Battery Saver Relay". Where are these located?

 

[CDW6212R]

Be sure the door ajar light on the dash works, and that it goes out when the five doors are shut. The latches and strikers have to be working right to shut that circuit down.

The "interior lamp relay and the Battery Saver Relay" should be in the small relay box under the dash. look under there to the right of the pedals, to the left of the radio. You can with difficulty get into it and R&R the relays, maybe one of those is fubar. The GEM module is also part of that control circuit, hopefully it isn't that, which is much more expensive.

 

[J_C]

It could very well be that your interior light, or battery saver relay are bad, but something is being overlooked!

Battery drain should settle down to 2 or 3 dozen mA when the vehicle is off, but there is a woke state where it is normal to draw over 200mA. This woke state is triggered by various things such as opening a door, reconnecting a battery, putting some fuses back in, etc. There has to be a period of electrical inactivity for around 45 minutes for it to go back into the lower power state of ~25mA.

You don't have to jumper the door switch, simply open the door and flip the latch mechanism closed manually... just don't forget you did that and try to close the door with the latch engaged still. Wait a least 45 minutes, then test.

One test you can do is use a multimeter to measure voltage (mV range) drop across the fuses, but only if they are still (original factory or) major brand fuses, the readings will often be inaccurately low with generic Chinese fuses.

I don't know if the following linked pdf is the *best* writeup of how to do it but it is one of them. Others or just fuse charts with the mV readings expected can be found web searching something like fuse voltage drop current pdf.

https://www.meeknet.co.uk/E64/Fuse%20Voltage%20Readings%20To%20Give%20Current%20Readings.pdf

Also, disconnect the cable to the alternator (at the alternator) and measure for current flow there (between alternator stud and cable connector) when the engine is off. There should be none. Alternator could have a leaky diode.

 

[Wildings]

Look for any other odd electrical symptoms, for example do the fog lights stay on with the engine off. It may be a wiring issue from someone working on something, or as simple as an old sticking relay. My 98 Mountaineer did that many years ago, the fog light relay was leaving the fog lights on. I threw that relay away and installed a spare one.

If nothing is obvious, then begin to remove fuses one at a time, that can take a lot of time, but it will narrow it down.

I had a battery drain problem ×it my 2008 Mercury Mountaineer...solenoid had failed that allows key to be removed from ignition when shut off. Buried under shifter, so I just shut car off and locked with key in ignition. Battery drain was from the auto seat position function which activates when engine shut off and key removed. Computer was confused by key in ignition, car off and locked for long periods. I don't understand exactly, but that system might be something to check if you have the 2 person seat position memory option. Good luck!

 

[Loren Smith]

I had a battery drain problem ×it my 2008 Mercury Mountaineer...solenoid had failed that allows key to be removed from ignition when shut off. Buried under shifter, so I just shut car off and locked with key in ignition. Battery drain was from the auto seat position function which activates when engine shut off and key removed. Computer was confused by key in ignition, car off and locked for long periods. I don't understand exactly, but that system might be something to check if you have the 2 person seat position memory option. Good luck!

I don't have that feature but thanks for the info. Good stuff!

 

[Loren Smith]

I don't have that feature but thanks for the info. Good stuff!

Well. Good news I think!! I replaced the battery saver relay and the interior light relay. They were cheap to my surprise. But still had the 200ma draw and it didn't go away. Then by chance I touched the interior light dimmer switch/wheel and the lights flickered . Then I discovered if i just tap the dash, the lights flashed. I then replaced the dimmer switch. Hooked everything back up and connected my meter. When I open and close the door, the meter reads 1 amp till the lights go out, then it reads 200ma. After 45 minutes, the reading dropped to below 50 ma. Hopefully I got it. Gonna watch it for a few days and see if the battery goes down.

Thanks for all the great advice. Could not have gotten it without it.

 

[Loren Smith]

Well. Good news I think!! I replaced the battery saver relay and the interior light relay. They were cheap to my surprise. But still had the 200ma draw and it didn't go away. Then by chance I touched the interior light dimmer switch/wheel and the lights flickered . Then I discovered if i just tap the dash, the lights flashed. I then replaced the dimmer switch. Hooked everything back up and connected my meter. When I open and close the door, the meter reads 1 amp till the lights go out, then it reads 200ma. After 45 minutes, the reading dropped to below 50 ma. Hopefully I got it. Gonna watch it for a few days and see if the battery goes down.

Thanks for all the great advice. Could not have gotten it without it.

OK, here's the latest. If I hook the battery up, in 2 days, it won't start the truck. Voltage is at 11.9-12.0. I re-hooked my ampmeter and charted the draw again and it is the same as before. I see 1.1 amp draw for about 4 seconds, then it drops to 200 ma for about 40 minutes, then it drops to 16-20ma and stays there. From all the info I've rec'd, that seems normal. With all that said, maybe I got a bad battery.

 

[J_C]

Charge the battery, disconnect from charger and wait a few minutes for the voltage to settle and measure it. Next leave it disconnected from the vehicle for several hours and see how much the voltage drops. It should have practically no drop while disconnected.

Since the drain drops to 20mA after 40 minutes, I still wonder about the alternator, if it is draining through it or did your drain test take that into account?

If all else fails, take the battery back to seller to be tested, at 11 mos. old it is probably under warranty still.

 

[Loren Smith]

Charge the battery, disconnect from charger and wait a few minutes for the voltage to settle and measure it. Next leave it disconnected from the vehicle for several hours and see how much the voltage drops. It should have practically no drop while disconnected.

Since the drain drops to 20mA after 40 minutes, I still wonder about the alternator, if it is draining through it or did your drain test take that into account?

If all else fails, take the battery back to seller to be tested, at 11 mos. old it is probably under warranty still.

I did disconnect the alternator to check for any draw there and there was none. Battery is going back tomorrow. I charged the disconnected battery the other day and when I disconnected it, it showed 12.8 V. Dropped to 12.3 after 8 hrs.