Electrical: mystery power draw

after 9 alternators in 4 years i have now replace the battery 3 times & i installed a new ecm…runs better now…still killing batteryX w/i a few hours over night.(thus altern.) it always jumps off & alt. will charge bat. no prob. i think it may be a lapse in radio circuitry. b4 radio died, it had to be turned off manually. it is the factory radio, so nobody has messed w/ the constant wire. i gave this car to a recently laid off single mom for her 16 yr. old, thinking i could replace the ecm for them & all would be good…& it is running great if it would just stay charged! could a bad relay for the radio do this? where is it? i feel sure it’s one of the 4 relays beside the fuses under the steering wheel (def. not in w/ relays under hood…or @ least not labeled indicatively) these 4 are the only ones not labeled in the car! btween 2 jobs & school(& the fact that i am a novice w/ cars & know what i know by necessity to fix my own cars) i have little money to pay $75 an hr. for diagnostic, & little time to borrow a voltmeter to test it. PLEASE HELP!! THANKS!!! A SHADY TREE MECHANIC, BARBIE (yes, unfortunately, that is my real name!)

unfortunately you are going to need a voltmeter to test it. There are a few ways, but the easiest i have found requires 2 voltmeters. first take the negative lead to the battery loose and connect to voltmeter in series of the ground circuit with the meter set on millamps. This will let you know how big of a draw you have. Most cars have a draw of about 35 or less (.0035 amps) after you set the meter up you might have to wait a bit for the car to “sleep” usually about 15-20 minutes depending on the car and computers it has. after the car has gone to sleep take the other meter set onb millivolts and check every fuse. if the meter reads andything besides 0.00000 there is a draw on that circuit. Example. if you set the leads on the radio fuse and it read 0.03 mv then there is voltage being eaten by that circuit. pull the fuse and check the other meter to see if the draw has gone down. Once you find the draw trace wiring for any shorts to ground or power. If you don’t find any disconnect any loads (lights, computers, switches, ets) that are on that circuit and recheck to see if your draw is gone. it can be very time consuming, but makes you feel unvbeleivable when you find and repair a battery draw. if you do take it to a shop the labor for a draw can get very high very fast.

hope this helps

thank you so much!! i have the weekend off & an air conditioner repair guy as a friend w/ a voltmeter @ my disposal so i’m going to get to it!! i’ll get back on & let u know how it goes…3 years from now when i track it down!! : ) j.k. this will likely narrow my time down a lot…i’m not a mechanic, but i’m all these two have to help them out (bless their hearts! : )) so i do what i can. the kid the car is for is a real trooper & is very grateful for my poor lil ran down car…he deserves any help i can give them. thanks so much for your help! p.s., if it matters, when the ecm went out,as usual, the speedometer, windshield wipers, radio, & rpms went nutty 1 by 1. & once i replaced it (tight squeezed, b.t.w.) it ran much better & all went back to normal xcept the relay in the w.s. wiper motor was bad(replaced it) & the power was still drawing…is this indicative of anything? is it possible it sent a surge that blew another relay? it was suggested to me that it was likely the radio or accessories. this may seem redundant since your response gave explanation of how to answer that, but i thought this info might give me a better place to start to save time!! is the prior state of the radio(staying on when the car was off & playing still, after the display quit)indicative of anything? sorry for the looong
reply!..that was less of a post script, & more of just script, wasn’t it!!
thanks, barbie

Here is a helpful article which adds details to johnnykral’s notes: http://www.aa1car.com/library/battery_runs_down.htm
It might not have been covered to check power drains through the starter and alternator. Both parts can have internal current leaks to ground. The wires which connect to both are from the positive battery post. The terminal on either has an insulator to prevent a short to ground. Be sure there is a plastic on the top of the battery positve post; otherwise, a short to the hood (when it’s closed) is possible.

“a short to the hood…” This would not be a mystery; within seconds you’ll see smoke and the paint burning off the hood!

thanks for the info…to both comments…also, i was going to pull the starter & have it tested, but it’s a sideways engine & i can barely even touch the end of the starter that DOESN’T have the bolts! however, as i should’ve already mentioned, a very distracted auto parts employee @ the store where the 16 yr. old bought the new battery, was testing the batt. after i replaced the last alt. & she said the positive cable was bad…let me also mention it was during the iron bowl & she was obviously not into providing much service b/c she didn’t even offer to charge the batt. for him…he was checking about swapping it & she said ‘i can’t change it out b/c your pos. cable is bad, but the batt. is just low’…it that even detectable from a auto parts store’s diagnostic machine? i have had one of the places that put on 3 of the first 6 alt. on test the power “system” & find no problem…i now install them myself & have bought a new one w/ a lifetime warranty…i’m on the 3rd of these!! i would just change out the pos. cable, but as i said, i can barely even touch the starter. does this even make any sense or was she just lazy?
thanks! learning as i go!! barbie

Some auto parts stores can do the battery and alternator checks at curbside. The battery does NOT have to be removed. I’m not sure of the validity of tests on a battery which is partially discharged. I just don’t know that test equipment.
A cleaning might be all the positive cable needs. Use knives, or wire brushes, or sand paper, or files to remove the corrosion from the inside of the terminal.
Starters and alternators can be the source of electrical drain if they are defective, or if the connecting cable terminal is touching the body of the part. You can check if any current is flowing through the starter by disconnecting the positive cables from the battery. Then, disconnect the short wire which goes from the positive battery terminal to the fusible link box and the fuse box in the engine compartment. Connect the amp meter between the battery post and the cable [electrical series] which goes to the starter. There should be no current flow.

The trouble you are having isn’t caused by a bad starter so don’t waste your time checking that. The starter is only connected when the starter solenoid is activated so no current can flow to the starter motor (and drain the battery) until the solenoid is closed.

I think the alternators are failing due to a problem in the wiring for the charging circuit. The trouble may be causing the alternators to put out a full field charge which makes them work harder than they should. The battery sense lead handles that area. The trouble may also be in the lead to the battery or grounding. You are going to have to understand how the charging system works in order to find the trouble. You should also have a service manual for the car to guide you. Not to discourage you but, what you trying to do some shops even have trouble with due to lack of knowledge in the electrical systems of a vehicle. A good shop that specializes in electrical trouble could handle it though and we will help you as much as we can.

thanks so much! i will say this, i do have a chilton’s for the car & i have replaced the terminal on the positive cable around alt. #4 cuz it was cracked up the side & would work itself loose. i had someone else do it b/c i don’t trust myself w/ wiring unless it’s on a wire harness…so no corrosion in it. thank you guys for your help! in this economy & such i just can’t afford the diagnostic test. i’ll let you guys know what happens. i’m bull headed enough to keep tryin!! DOES ANYONE THINK THE RADIO ISSUE MIGHT BE THE PROB.? I’M GONNA TEST IT FIRST, BUT IS THAT EVEN LIKELY? THANKS TO ALL OF YOU! WISH ME LUCK!!

Hopefully you have a meter to check current with. If you don’t then get one otherwise you will be wasting your time which you stated you have little of. By using the link that Hellokit provided you can see how to find current drain problems. If you think the radio is the trouble then just pull the fuse to it and check the current drain with the current meter and compare the readings before and after the fuse is pulled. As it was stated earlier, a current draw under 35 milliamps is normal for most cars.

awesome! thanx! i do have a meter available…& hopefully i can get hold of 2(as per the first response to my problem! NEW QUESTION: does anyone know where to get a blue book value on a vehicle as it was two years ago(insurance issue…guy hit my truck almost two years ago…finally getting claim filed) i can only find the current blue book on it. does anybody keep the old values on file? i’ve checked on the kelly website & all over on line…the best i could do was to put the spec.s for the vehicle @ the time in the current listing…which is still less than it was then.
i know what the blue book was on it then, but i’d like to have a printout just in case i need it! thanks for all the info. i’ll get back on when i solve the power issue. barbie

Can you CLEARLY state what activity is happening with the radio and why you think it could be the cause of whatever aills your car (you could clearly state that also). Like "my car has this problem…my radio also has this problem…do you think the two are related?

Please leave out all information regarding single mom,you economic situation,social challenges etc.

Just lay out the technical facts regarding the radio,keep it simple and don’t add anything that revels your bias towards the problem being caused by the radio,facts only.

You don’t need two meters. Just one to monitor current with. While I understand the advice given about using the second meter I think it can lead a person down the wrong path. Some things draw current normally while the car is off. That method could lead you to chasing your tail if you don’t know what you are doing. By just lookng at the current drop when pulling fuses it will tell you where the excessive current path fault is.

To everyone who has helped me out on this…thank you! i was unable to get hold of the voltmeter last weekend, so i charged the battery & tried pulling the fuse on the two things i thought might be drawing on it…the radio & the security system. when this all started, i noticed the security light flashed constantly (& i was pretty sure it didn’t do that before). i pulled the fuse on it first. it was the fuse labeled ‘electronics’(i think) two days later, the battery is still full charged. so that was the problem! (how lucky was i to find it right off?!?) there are 3 relays to the sec. syst. i’m going to replace them & maybe that will do the job! right now, the anti-lock & airbag lights are on(w/ that fuse pulled) but it’s running great! if anyone has any input on this, let me know…i still don’t get how a little light could kill the battery over night…even in just a few hrs. some times??? thanks again…i’ll be looking for your input. MERRY CHRISTMAS! barbie

i included that info because i knew the first thing that would be said was “you need to take it to a mechanic” if i hadn’t felt it was pertinent, i wouldn’t have included it. thanks anyways…i’ve found the issue. MERRY CHRISTMAS oldschool…now THAT was not pertinent info.: ) barbie

thanks cougar,(re: your 2nd input)! this worked! haven’t completely solved issue yet, but i pulled the fuse to the sec. system(electronics was the label on it i think) & it’s not drawing power now…it’s been almost a week & all is good…i thought i might try to replace the 3 relays that go to it…you think that may be where prob is? the reason i checked the security fuse is that when all this started…in addition to my radio going nuts…the security light started flashing constantly…& i felt sure it didn’t use to do that. my boyfriend insisted it always had…but he didn’t drive it. thanks for your help. let me know what u think of the relay replacement, if you have time.
merry Christmas. -barbie

Don’t you feel an obligation to tell everyone who tried to help you what the problem was? and I will double down on your "Merry Christmas"with a “Happy New Year” take that!:slight_smile:

Is there some reason a single mon can’t still be advised to “take it to a mechanic”?

Replacing the three relays in the SRS(?), security, and radio system has no purpose. Relays can go bad; but, until there’s some kind of reasoned proof that they are bad, it’s futile to just change them.
You don’t want someone to advise you to, “Take the problem to a mechanic”, because you are “bull-headed”, is your choice. The people who have advised you to do that have assessed your abilities, on the information you have supplied, and decided that you need the help.
If you think that you can handle it, you now need the wiring diagrams for the circuits which you have isolated the problem to (by pulling the fuses). You’ll also need to operate that electrical multimeter. Let us know when you have repaired those circuits, OK?

hey guy…i did fix it…& you’ve got to relax…you’ve gotten way off path. that kind of angst will kill you! you say bull headed…i say diligent! this forum is to help people that have more diligence than cash. vehicles are cause & effect. i’m in chemical engineering & i have always managed to fixed my montero & my pathfinder when i put my mind to it with the same logic required for my degree. i’m sure you didn’t always possess the knowledge you do now…someone taught you…likely w/ patience & tolerance…you should try it. life’s too short to not treat people the way you’d like to be treated. have a good night. thanks again to everyone that helped me! lucinda

thanks for the double down! it was the security system…i think…someone gave me a cd player to put in the kids car & a wire behind was near bare…but also i replaced 3 relays & all’s been good since.??! p.s. i’m not the single mom…she’s the one i gave my old car to for her kid to get to work & school…she’d just gotten laid off…so $$$ was the reason… as usual for all of us! some things you HAVE to have a mechanic…but every now then you come across people to help you out. Thanks again!