Dead battery, Alternator or Vampire Draw

Hey Guus,
I’ve got a '96 Olds Aurora 4.0 Ltr V8 and if I let it sit for 2 days, the battery is dead as a doornail, hardly juice to light my dash. First thought is a dead cell, but it will restart after a jump, and even the following day so I’m having trouble isolating the battery or alternator, or a vampire draw from an alarm etc. I did have an OBDII run and the error pointed to my ECM (the “brain” of your car) but that shouldn’t affect cold cranking amps…
This is the Northstar Caddy motor with a gigantic battery if that matters, it takes like 840 to kick this beast over…
Please save me from buying a $200 battery I don’t need and tell me what you think? Thanks

You can test each cell of the battery with a hygrometer. You can test for a vampire draw with an ammeter.

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Some parts stores will test your battery/charging system for free.

But if you’ve got a code pointing to a problem with ECM, the ECM is what regulates the voltage from the alternator.

So keep that in mind too.


how old is the battery?

Do you park outside?

How cold is it when you try to start?

Apparently you have a side-post type of battery. First thing you do is check the connections. Grab the cables and try to move the connections. If you can move them by hand, they’re not tight enough. Also, you need to remove the red and black rubber, so that you can get a really good luck at the battery terminal bolts and the cables. I wouldn’t be surprised if you find a lot of corrosion, or maybe the bolts are stripped. This is very common. If you need the bolts, just about any auto parts store will have them in stock, and they’re cheap

If the battery’s over 5 years old, just be proactive and replace it. Its best days are almost certainly in the past

if you want to perform a parastic draw test, just google the procedure. 50 milliamps is the absolute limit, and I’d like to see 25 milliamps or less.

I’m assuming you had no starting problems in the summer and spring, when it was much warmer . . . ?


Clean and tighten the battery connections. If that doesn’t fix the problem, charge it up with a battery charger, then take the battery to a shop and have it load tested. That’s where I’d start.

OK George, this goes for the rest of you Pros db4690, Tester who have always helped me… I replaced the battery, it was only putting out 500 cold cranking amps. It’s not dying any more, but often I have to turn the key 2-3 times before it “responds”. The car is clearly not running right, if I accelerate even a bit too fast, it backfires, it’s fine at cruising speed, but it’s obviously not running on all 8. In the old days, I’d question the timing. Other info you may need; The fuel pump is “louder” than normal at idle, not a broken sound, just like it’s working harder than usual. My gas mileage is crap, 13-14 mpg, and 90% of my driving is around the neighborhood, not 65 on freeways. I have changed the plugs, wires, oil change, tranny filter and radiator with flush and battery. On the OBDII test the last message was P0603 PCM Keep Alive Memory Error/Reset. I obviously don’t want to replace the PCM until I know it’s at fault. What do you think guys? Thanks so very much

I replaced the battery, it doesn’t die any longer, but I often have to turn the ignition key 2-3 times before it responds. My error code is P0603 which is “Keep alive memory fault/reset”, after study I learned my car is in “limp mode” and not learning new driving parameters. From my reading, it says the most common issue is the battery connection (we know this to be good with the new battery), bad ground wire to the PCM, and this “Charging system fault Ignition system fault causing secondary ignition voltage inference”. I don’t know how to check the PCM ground and I don’t know what the above charging system fault means, but that would explain a great deal since my car won’t start right away (ignition voltage) wouldn’t it?

Cold weather plus local driving only is the recipe for the worst possible fuel economy short of just letting the car in your driveway (0 MPG!). However, there is clearly something else contributing. Perhaps the spark plug wires aren’t routed properly or have been reattached to the wrong plugs.

you keep nursing this aurora along. i say move on. if you want to keep torturing yourself on this northstar clone and electrical nightmare, get a last year eldorado. at least it has a little class. seems to me the 0603 code is when you disconnect battery. it just tells you the battery was unhooked and really means nothing. my last STS avg’d 14mpg in town. thats normal

Please see my updates to George and db4690, it is acting like we have a connection issue somewhere, the notes say the PCM is the last thing to assume, my code is because my car is in “limp-mode” and running badly because it’s not learning my driving conditions, it’s in a default state. We know the battery is now good (replaced last week) and well-connected, so your voltage regulation holds water. It’s not starting right away, I usually have to turn the key 2-3 times, I imagine I need to find the ground wire to the PCM for starters? Thanks much

Hey Cavell, I always respect your posts, unfortunately I don’t have the funds to buy a car right now, I’m on disability and dealing with spinal damage (got hit by a mail truck on my Ninja and blew 10 discs) so I have to get this running to get my boy to and from school. What should I check next, ground wire to the PCM?

Also, I’ve paid a pretty penny fixing so many things, the engine is sound and we’ve taken care of most major components, it’s just the minor electrical issues and I worked on cars in the 80’s when you didn’t need to read a wiring schematic to fix your car, and I know I’m close to solving this problem.

I learned that my car is in “limp mode”, so every time i start it, it doesn’t recall any of the settings, timing, air-fuel ratios, nada, so the challenge appears to be what’s not connected. The most common cause of code P0603 (PCM Keep Alive Memory Error/Reset is battery or connections. We put a new battery in last week so we know it’s not the primary cables, so we’d have to look at the ground strap, the ground wire to the PCM itself, we already changed the plugs and wires…it would also help if I knew where the PCM is (-;/

I’m presuming you mean it won’t crank intermittently with the key in “start”. You might hear a click, but it doesn’t crank the engine. Is that correct? hmmm … Maybe that’s a clue to the performance problem. The starter motor draws a lot of current, often over 100 amps. That current comes from the battery positive post, goes through the starter solenoid and starter motor, then returns back to the battery’s negative post. One idea, there’s a weak ground somewhere between the starter motor and the battery’s positive post. Check the ground wires for the transmission and the engine, make sure they are touching clean shiny metal on the chassis and the transmission/engine. Also check where the battery negative wire attaches to the chassis, make sure that’s touching bright shiny metal. Good idea to verify the starter motor is firmly attached to its mount of course too, that’s where the ground connection from the starter motor begins.

I wouldn’t suggest the above is the most likely if no-crank is the only problem you had. For a no-crank, the problem is usually either the battery or the starter. Since you’ve replaced the battery, then the next guess would be the starter. But b/c your code seems to say you have some kind of weird electrical problem going on, that combined with the no-crank makes me suspicious of a ground problem between the engine/transmission and the battery negative post. If your Aurora is front wheel drive, take a look at the CV boots. Any signs of heat damage or distortion? That can occur with grounding problems, when the starter current is forced to through the axles to reach the chassis ground.

The ideas about ignition system or alternator interference also suggest a grounding problem. Make sure your alternator is well grounded, no plastic spacers etc preventing it’s case from making good contact w/the engine. Faulty alternators and coils can emit interference on their own of course. You’d need an o’scope to diagnose that; most diy’er would just swap the alternator or the ignition module/coils with known good parts to see if that solved it.

My guess, bad ground connection somewhere between the engine/transmission/chassis/battery negative post. One way I’ve diagnosed that is just run some more ground wires in parallel to the existing ones and see if that helps. Best of luck.

Hey George,
Wow, I don’t know cars the way you do, but I did when cars weren’t computerized and I’m a monster at Google research, and ground wiring was my conclusion as well. My biggest challenge will be I don’t know where any of my ground wires are, not even the strap. If I can’t find a reliable shadetree mechanic, I suppose I’ll have to take it to a shop that specializes in auto-electric…but that’s my last choice…the ones I called a few weeks ago wanted from $90-$130 to scan (I could buy an OBDII for that), then the work itself is a separate charge. That makes this $300 when you add just 2 hrs labor…That would really “sting” to shore up a ground wire or two. I think I’ll start by using your list and either Google each component to find their grounds or pick up a Haynes/Chilton for the 96 Aurora. I’d like to answer your question and provide more info if I may…

Yes, you are correct, sometimes I will turn the key and for just a split second it behaves like a dead battery, (but it’s not, I have my control center set to show me my battery charge 24/7 right now, and it hasn’t dipped below 12.2 even during the quick no-start, and it jumps to 15.1 when the engine is running. This may be unrelated, but I’ll let you be the judge since more information can only help you. In the past few weeks before I replaced the battery, all my interior lamps are dead, the roof when you open the door, the door lights, exterior side lamps, even the audible “dongle” sound when you open the drivers door. I used a test light and the lamp’s fuses won’t light it up, (I put brand new fuses in each, but none were blown anyway, my cruise control went out, my trunk release (fuel door same unit does open) and I just replaced that switch…that’s an awful lot of stuff gone out in a very short amount of time.

If you have an accurate volt meter, suggest to monitor the battery voltage from time to time. Even once a day, just before you start the engine for the first time of the day after it has been sitting overnight. It should be constant day to day & very close to 12.6 volts at temperatures above 40 degrees F. Keep a record for 2-3 weeks. If you see a slow downward trend, could indicate a charging problem or vampire draw.

I need your help George, as I don’t know what to try next? I’ve replaced the battery, all new plugs and wires, all new fluids and filters, tranny, radiator, oil…
The car is clearly running in “limp-mode”, I have to turn my ignition key very far to start it, if I do the routine quick twist, it doesn’t start sometimes…but it does start every time…and no, the starter isn’t going bad, I know what that sounds like. Other symptoms, my car is doing a little “bump” about every 10 seconds at idle (at a stoplight), so it’s “missing”. If I accelerate too quickly, instant backfire, if I accelerate gradually it runs perfectly. It runs fine at freeway speeds. My last OBDII check said P0603 PCM Keep Alive Memory Reset Error. It’s unlikely my PCM is shot, more like a ground issue somewhere, but I don’t know where to begin…and the battery terminals are tight, perfect and clean. I don’t know where the ground strap is on my Olds Aurora, nor the PCM ground wire, these are probably good places to look, yes? Thanks G

Is this still the case? If so, that’s where to start. Ask you shop to measure the phantom battery drain current. It should be less than 50-75 mA.

It should be 50 milliamps at the most

25 milliamps or less would be preferable