electrical drain killing battery - '98 Ford Taurus LX
'98 Taurus LX, 3.0 Vulcan - your basic ex-rental car options. Battery tests fine. I have a low/almost dead battery after car sits about 48 hours or more. Alternator puts out a solid 14.6V no matter how much load I put on it. Plugged in the multi-meter (set for current draw) and found 270 milliamps are going somewhere with the key in the off position. Started pulling fuses and isolating circuits. Alternator & relays not pulling any current. Radio draws 40 milliamps for its' memory. The only other circuit drawing power was the Battery Saver 10 amp fuse - it's pulling 200 ma. That must be it. I don't really need the battery saver feature, but leaving that fuse out, the power windows don't work - probably affects some other accessories too but didn't check them all.
My Chiltons manual doesn't address how the battery saver circuit works. I assume it disconnects the battery after a period of time when we leave the headlights on, or the door open, or something else that draws power.
Didn't know I had this feature until I found the fuse for it listed in the manual. I doubt that this circuit even works on my car because when my door latch switch stuck and the interior lamps stayed on and killed the battery a few months ago, it didn't do it's disconnect thing. I sprayed the latch liberally with penetrating oil, slammed the door a dozen times and the light went out as it should. Thought that fixed the issue. No further problem till now.
I see in the Chilton manual there's a relay called the battery saver relay - could this be at fault? Can anyone tell me how the battery saver circuit operates and what components does it include?
The battery saver relay is controlled by the Generic Electronic Module (GEM) and is located in the fuse junction panel.
The battery saver relay is designed to supply B+ voltage to:
Dome and map lamp switches.
Glove compartment lamp switch.
Cargo lamp switch.
Interior lamp switch on headlamp switch.
Interior courtesy lamp relay.
Delayed accessory relay.
The battery saver relay prevents excessive battery drain by interior lighting circuits. The battery saver relay operates as follows:
The GEM supplies a ground signal to the battery saver relay anytime one of the wake up inputs of the GEM is activated.
A wake-up command is sent when:
Any door becomes ajar or is opened or closed.
The ignition key is inserted or removed in the ignition switch.
The ignition switch is turned from OFF to RUN.
The ignition switch is turned from OFF to ACC.
A wake-up request is received from the remote anti-theft personality module.
The driver or passenger door lock cylinder is turned to unlock.
The GEM will maintain the ground input with ignition in RUN or for 40 minutes from the last input activation with ignition switch in the OFF position. After 40 minutes the ground signal is discontinued.
This de-energizes the battery saver relay, preventing B+ voltage supply to the controlled switches and circuits.
I'd make sure the GEM times out after 40 minutes before examining the ammeter reading- leave the meter attached and on for the 40 minutes and then read the meter. If it's still high then just examine all the items listed above.
Master ASE Certified L1 Chrysler Technician- still a Ford fan at heart.
1964 Thunderbird Hardtop- Chantily Beige- 390 FE 4V V8-Uncle's Car
1966 Thunderbird Convertible- Red- 390 FE 4V V8- Uncle's other car- waiting for paint and body work!!!
1967 Mustang Convertible- Blue- 289 V8- helping a friend re-assemble this classic
Thanks for helping guys!
SHOZ123, I agree – 40 ma sounds too high for the radio memory – it did seem to drop down after a period of time.
TBIRD, thank you for the great information! Following your suggestions, we let it sit for an hour, came back and found it only drawing 7ma total. Disconnected the battery and re-connected and it returned to 270ma. After a minute, it drops to 180ma.
We’re going to let it sit another hour and re-test. I’m now thinking it might be an intermittent relay sticking on. Maybe the battery saver relay? Or maybe one of the wake-up triggers is staying active? We’ll repeat the test several more times today and report what happens.
Hello, Did you ever find the source of the battery drain? I have 2003 SEL with same problem. After 48 hours dead battery. It appears that drain is associated with fuse No. 26 Perhaps battery saver circuit.
It looks as though the drain I was describing in my last tests are perfectly normal. I changed out the battery and the problem never happened again. I can only assume there were problems in the old battery even though it load-tested pretty good at the time. I still have the old battery sitting in a corner and last time I looked, it still had around 12 volts on it.
btw, the battery I'm using now is an original Mopar unit that came out of my Mom's '99 Chrysler 300m. We replaced it in 2007 thinking it must be on it's last legs. It sat a year in the garage and because of the Taurus problems, I took a chance on it after giving it a charge just to see if the battery might be problem. It's a bit bigger than the correct battery and barely clears the hood. It has been working fine in the car ever since and I plan to see how long it'll go before it gives up. 11 years and counting....
Similar problem, in that I've isolated a ~230mA drain through the battery saver relay fuse. I'm experiencing dead battery problems intermittently, most recently in only about 5 hours. If the GEM resets when the fuse is removed and reinserted, I haven't checked if it is resetting properly. The dome lights are not lit, and I can't see any other obvious drain.
Possibly related: In the morning after a heavy frost, the door mechanism felt frozen. More force than normal is required to unlock and open the door, and it seems like the cable or latch jams to the 'open' setting. I used a screwdriver to force the latch into the closed position, observed dome light off, and let it thaw. After thawing, the door appeared to operate normally.
I suspect that moisture freezing is causing the door latch to intermittently indicate 'open', waking the GEM and energizing the battery saver relay. I've got the driver's door torn out now so I can inspect the mechanism if if freezes in the coming few days.
Is there a way to test the electronics without spending 40 minutes holding a meter to the connection? Or an easy way to determine what the wake-up signal was?
Sorry if bringing up an old thread violates etiquette here.
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