Battery Leaking while parked

4610 Views 44 Replies 8 Participants Last post by MsSpinks, Aug 23, 2007

spoonman449

Discussion Starter · Jun 26, 2007

My 99 STS loses voltage while parked. Initially I thought I had a dashboard problem since the weak battery was making the display freak out (all kinds of erroneous error codes, even went completely black on occasion). Well now I know it's a simple case of battery weakening to a point below the min required voltage while the vehicle is turned off and parked. (I know this since when I religiously disconnect the battery while parked - all is well)

Any tips on how I can find the leak efficiently? I am thinking about a divide and conquer method by removing fuses and looking for the guilty circuit.

I am attaching a snippet from my dealer's attempt ($672.35 for battery and diagnostic efforts) to diagnose this thing and wonder if there is anything here to help me narrow down my search.

Thanks to all help offered!

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1 - 20 of 45 Posts

93STS#1

· #2 · Jun 27, 2007

Could be your alternator...

chubbyranger

· #3 · Jun 27, 2007

Have you checked to see if the alternator recall was performed on your car? 98-99 had bad alternators that could catch fire for no apparent reason, even if the car is off. Call a dealer and give them the last 8 digits of your VIN and have them check and see if it was done. Would like to believe that your dealer did this as step 1 but I had to argue with one dealer to convince them there was a recall in the first place. Could be your culprit.

Submariner409

· #4 · Jun 27, 2007

Agree...a bad diode in the alternator would run down the battery......so would a faulty switch in the trunk light (but the 99-04 series has timers to shut down unused lighting after 10 minutes or so...) You might have to pull each fuse, one at a time, in the front and rear boxes, and jump across the socket with a sensitive DMM.

spoonman449

Discussion Starter · #5 · Jun 27, 2007

I have a DMM (it's a cheapie) that has a 200 microA setting.

Thanks for the tip on the alternator.

If the alternator is suspect, I am wondering if I can (as an experiment) disconnect it instead of the battery, leave the car parked and see if I get a sunken Voltage or not. Yeah?

As for removing a fuse and putting a DMM in place - I would imagine some circuits SHOULD show a draw while parked yeah? In that case, I would need to know expected current levels.

chubbyranger

· #6 · Jun 27, 2007

Some fuses should have small draws, some not. I will consult FSM to see if there is a spec. Yes, you can disconnect the alternator as a draw test and I would pull both the connector and charge lug. If the recall isn't done its a really good idea.

chubbyranger

· #7 · Jun 27, 2007

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spoonman449

Discussion Starter · #8 · Jun 28, 2007 (Edited)

Hey thanks Chub. So yes - recall was performed in May 99. Check.

So what I've done so far is pull the back bench and unhood the rear fuse block. Oh what a pleasure to try and troubleshoot such a "smart car". I'm literally crawling in and out of my window so as to not trip the timers, relays and whatnot. Yeah yeah I'm sure there is a smarter way.

Couple observations - the Large relay in the corner mapped as "Cigar" is quite toasty warm, not burning, but notably warm after disconnecting / reconnecting the bat. Not sure if that is relavent to my leak. I have no accessories plugged in the cigar plugs and I don't think they are tweaked.

The other thing that I am wondering about is that 3 position slider switch up near the internal rear view mirror - has positions "off - auto - on". My understanding is that off means kill the interior lamps, on means force em on, and auto means hey car do what you think is right. I noticed I had it in auto and I wish I had checked to see if the toggle was "docked" solidly in that position. It's a slider and I am wondering if it was just a bit off the center position. I have now moved it to OFF. (Ooops - might now have thrown a variable into my trouble shooting context.)

I mean what is the state of the circuit when you are between the 3 spots? I guess what I'm getting at is could it be possible that I unknowingly am leaving the internal light circuit sortof ON (realizing I should see on ON light, but maybe the current is running elsewhere). Dunno. I could be way off track here but I just have this feeling that this leak is due to some REALLY simple stupid thing.

I haven't had success getting my DMM to show me a current reading. It's a cheapie. I put it between ground and the bat ground and it seems to only want to complete the circuit if I am in the 10A setting but I get know steady state current reading and I KNOW there is flow.

Just sharing and releasing here. Frustrated but determined!!!

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chubbyranger

· #9 · Jun 28, 2007

Off to work so this will be brief:

Put the ammeter across the fuse/relay terminals to see what each circuit is drawing.

Leave door open and test lighting and radio circuits for draw before and after the 10 minute timers are supposed to trip off.

Write down what you're doing as you go

Dome/interior light switch should not be a problem unless the lights were on all the time, but even then battery rundown should have kicked in.

Even with the recall done the alternator could still be a problem so keep that on the list of things to test.

Submariner409

· #10 · Jun 28, 2007

By some chance has an aftermarket gadget been tapped into the mentioned "cigar" circuit? That MAY be one circuit that is hot all the time, and something like an alarm or amp or who-knows-what may have been hooked up. Just a thought.

JimD

· #11 · Jun 28, 2007

spoonman449 said:
....
So what I've done so far is pull the back bench and unhood the rear fuse block. Oh what a pleasure to try and troubleshoot such a "smart car". I'm literally crawling in and out of my window so as to not trip the timers, relays and whatnot. Yeah yeah I'm sure there is a smarter way.

There certainly is an easier way. Use a screwdriver to trip the latch on the door. I do them all when I know I will be in and out of the car for hours.

Sounds like you could use a decent meter with at least a 10A ammeter selection. The Greenlee line of meters at Lowes are priced reasonably; I use a model DM-60.

For safety and convenience, I always insert the ammeter in the battery chassis ground cable. Remove the cable end under the bolt and alligator clip one meter test lead to that cable end and the other meter test lead to chassis ground. After 10 minutes, the current draw will fall to approximately 50 ma when all the systems go to sleep.

And are you confident the battery is not the problem?

eyekandyboats.inc

· #12 · Jun 28, 2007

just throwing this out there.
DOES YOU POWER ANTEANNA WORK ?

spoonman449

Discussion Starter · #13 · Jun 28, 2007

chub - I will do as assigned and report back. (Some of those smaller relays are a bitch to pull.) And I will keep the alternator on the suspect list.

I hear you on the interior/dome switch. I'll stay objective but when I found that switch - I just got this "feeling" that it has something to do with this fiasco. I did slide it to off and I left my VM on the bat all night and it has held steady at 12.48 exactly (which I assume is tad low due to all my testing, but held solid level all night nonetheless) This is with alternator and front fuse block in circuit as well as the rear fuseblock.

submariner - no known "parasites" are plugged in. The only jacks I know of are: 1 - to the left of the passengers feet and 2 in the rear "ashtray" (center one near climate control) I haven't looked to see if there is one in the trunk and I definitely haven't plugged anything in even if there is. Will look.

JimD - Thanks for the doorlatch tip. I went the window route since I didn't know if the switch was coupled to the hinge or the latch. I'll trip the latch.

I was trying my meter between the battery and the groundstrap. I'll do as you recommended and try between the chassis and strap. As for the car battery - It is new and yes that is not a guarantee that it's "good", but at this point I do not suspect that battery. I probably should change the ammeter battery even though I thinks it's up to par. (I speak of both bats since I am not sure which one you are asking about.)

I am attaching a pic of the meter I'm using.

eyekandy - Thanks but I don't have a power antenna. (At least that I know of).

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Submariner409

· #14 · Jun 28, 2007

A fully charged 12V wet cell battery will show 12.5 to 12.6 volts, unloaded for more than 2 hours. If it stayed at 12.48 all night, you seem to have found the problem. Automotive alternator/regulators are not too "smart", and are set to slightly overcharge a battery in order to compensate for short trips. That's why you see 14.2 to 15 volts on the DIC. A "smart" regulator, sensing a fully charged battery, will cut output voltage to about 13.5 and reduce amperage to just enough to "float" the battery on the existing load, preventing overcharging and unnecessary loss of electrolyte. (Gel and AGM batteries are sealed and recombine the hydrogen and oxygen produced by charging, so no vents are required.)

spoonman449

Discussion Starter · #15 · Jun 28, 2007 (Edited)

sub - thanks. I would like if it's licked, but I'm not doing any victory dances just yet. Not saying you are wrong ... just not gonna assume just yet.

Damn I wish I had done some measurements before I moved that dome switch. Then I'd have some proof. I suppose I could put the switch back where I think it was but I'm not gonna do that just yet. I'm going to focus on getting some reasonable current measurements.

The only other "state change" that I made to the system was disconnect / reconnect the front fuse block and alternator.

I also should mention that the passenger visor mirror light was not working until I "scrubbed" the slider switch back and forth and then it came to life. Wonder if that in conjunction with the dome switch could have been providing any current path.

I just gotta get the current measured so I can step beyond the theorizing and into some real diagnostic meat.

eyekandyboats.inc

· #16 · Jun 28, 2007

well a battery will show any voltage but once it is used the amp hours will go down and the loaded voltage will drop alot.

chubbyranger

· #17 · Jun 29, 2007

chubbyranger said:
Dome/interior light switch should not be a problem unless the lights were on all the time, but even then battery rundown should have kicked in.

So I could have been wrong...
Went out and tested the interior light switch in my car tonight. Interestingly enough, with the car off and a door open, when the switch is moved from "Auto" to "On" I can hear relays clicking under the back seat. Read through the FSM and sure enough the power draw is actually changing circuits between the two switch positions. And the main module controlling them both (drumroll here) is the Rear Integration Module (RIM), which your dealer pegged in their diagnostics. According to FSM the battery rundown is controlled by the RIM which sets a timer from activation, but the timer can be reset, such as opening another door. I'm wondering if you bridged the two circuits when the switch was in-between and somehow confused the RIM into believing it was being constantly reset. :hmm:

spoonman449

Discussion Starter · #18 · Jun 29, 2007 (Edited)

Well I returned that POS DMM and bought a slightly better one.
I have the red lead in the 10A input and the meter is between the battery ground strap and the chassis.

I hook up with all doors closed and dome switch in off position.

Dash clicks and clacks, DMM is set to A and shows 4.75 - 5 and bounces for about 30 sec.
Then drops to 1.16 for about 30 sec
Then drops to .35 for about a minute
Then drops to .22 for about 30 sec
Then drops to .18 for about 6 minutes
Then drops and holds at .01

10 mA steady state? seem right? Not sure if I trust the meter but that's what I'm getting - I think.

If I turn on the rear reading light at that point it swings up to .95

JimD: Not sure if I buy the "trip the doorlatch with a screwdriver" since my dash computer reports the door as open even though I have the latch closed. Hence I am still doing my tests with doors shut.

Chub: Thanks for taking the time to test your dome slider. Your "RIM confusion theory is interesting", the other thing I am wondering is a sometimes sticky relay? Don't know what reasons the RIM has for resetting but an unjustly sensitive security trigger? or any trigger for that matter? That would somewhat explain the sleeping state to look reasonable then when I leave it alone it could be sneaking in a reset that goes unobserved. BTW - what is "ALD connector" mentioned in dealer diagnosis?

I am hoping to see offense at the Macro level of measure to determine that YES indeed there is current getting sucked while the car sits, but that 10mA seems reasonable (please set me straight if it isn't). I was hoping for there to be a blatantly too high number. I kept waiting and waiting and waiting but it just sits at .01 I hesitate to start measuring subcircuits until I prove there is absolute draw at the battery.

Not giving up.

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chubbyranger

· #19 · Jun 29, 2007

The FSM is atrociously unclear about an overall acceptable current draw level - it refers to calculations between sections that don't use the same units; in one place battery reserve capacity is quoted in amps and in another its in minutes. 10mA doesn't sound horrible when I look over the FSM table and add up the totals, but one of the techs here may have a better feel for it. I think ALD in your dealer diagnosis is old school for DLC (Data Link Connector) - the place where you plug a Tech II in. On my 1990 the diagnostic plug under the dash was called the ALDL - Assembly Line Diagnostic Link they may be using a shortened version of a previous generation term because I can't find a reference to ALD in the 99 FSM.

The part of the FSM I read is also unclear about what causes the RIM to reset its timer. I'm guessing if you leave a door open for >10 minutes and it shuts the lights down, you come back and open another door it should turn the lights back on and reset. Also I would guess if you open another door during the 10 minutes the RIM would reset. The bad/sticky relay theory might not be bad either, except if I recall right your RAP and light shutdown timers were working correctly, so it may be intermittently bad. Will try to read up on the RIM section after work and figure out what causes it to reset RAP and battery rundown.

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JimD

· #20 · Jun 29, 2007

spoonman449 said:
....
10 mA steady state? seem right? Not sure if I trust the meter but that's what I'm getting - I think.

Ten ma is an acceptable reading (my '98 settles down to 30 ma). A fresh battery fully charged should sit for 6 weeks or more and be able to start the engine.

JimD: Not sure if I buy the "trip the doorlatch with a screwdriver" since my dash computer reports the door as open even though I have the latch closed. Hence I am still doing my tests with doors shut.

The door latch clicks twice for the closed and latched position. And it sounds like you are done testing for parasitic drain anyway.

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