Electrical..no one could get a reading of my battery!?

Hey Guys,
Time to play stump the pros. My car was dead after 4-5 days not driving it (I know, a vampire draw most likely)…it was so dead my portable charger wasn’t enough to start it, I had to go car-to-car. I had Pep Boys throw a load on it and the inexperienced 22 yr old girl couldn’t get a reading and she asked me what my cold cranking amps were (I didn’t know, but it’s 840. Eventually she came up with 45% after I’d driven 6 miles. IMPORTANT FACT This is an Oldsmobile Aurora, meaning a Caddy Northstar V8 and a $170 battery…and it’s under the rear seats! I went to Auto Zone and got a guy this time who knew something about cars. He plugged into the positive terminal extension under my hood, and with a known-good ground, he got no reading! Finally he removed the positive and neg of the actual battery under my back seat and still nothing, he had to pull the cables and plug directly into the battery just to get a reading (65%) He told me he needed 70% to say if the battery was good or bad for sure, but the reading came back good. So, WHAT IS KILLING MY BATTERY GUYS? Do you all think my alternator might be the culprit? How do I find out when 2 car parts shops with special meters can’t tell me? Thanks again

How old is the battery?

On our Aurora, it was dead in about 3 days sitting at the airport with the trunk light on. It was so dead that the airport service guys couldn’t start it and it took the motor club to actually do it. I think I just replaced the battery after that. So really after a few days it could be anything draining the battery including a battery that just doesn’t hold its charge. People that have Auroras shouldn’t be concerned about spending a few dollars in my experience. At any rate if you ever get the battery up to an acceptable charge again, you need to go through the process of hooking a meter up and pulling fuses to determine the circuit involved and then checking the items on that circuit. I also had a blower control module that would keep the fan running all the time even if the car was off.

Corolla, It says 11/11 on a sticker, but I swear I replaced it like 2 years ago…Just to help you, I drive my car very little, I’ve been disabled for the years I’ve owned it…nothing but easy miles. About 8 per day taking my boy to school. It’s a 96 with only 115K…that’s 5400 a year, but my wife drove it 2 hours in traffic for a few years back in 2005. The past decade it’s only around town.

I should mention it’s had a ton of work recently, replaced intake manifold, oil pan gasket, tranny filter, brakes, plugs…and I’ve had many electrical components fail…the cruise control, drivers power seat, trunk release (but not the gas on the same switch panel) and when I turn the ignition on to start it, I can feel a split second hesitation that didn’t exist last week. It sat idle for 4-5 days and was dead as a doornail when I tried to start it yesterday.

Hey Bing. Yes, I’m just now experiencing the cost of an Aurora, they wanted $170 labor for the plug wires…just the labor, not the plugs or the wires!! I’ve replaced the AC compressor and the AC still bites! It only blows cold on the passenger side, and after I use a charge canister, my side will be “cool” for a week or so. I assume it’s the blend door, but I’m not paying to have my dash removed! PS The battery has already been replaced a few years ago, and this car is used very gently (low miles, mostly taking my boy to school 8 miles round trip. The battery is $170! I almost hope it’s the alternator or just a “vampire draw”, but I don’t know how to track that. Thanks again

Hey, I found a wire broken off under the hood, it’s about a 16 mm and you can see where it broke off, I haven’t put it back on yet. This single wire is on the left side of the engine block and was attached to a nut, it’s odd because I don’t know what it operates and there are no other wires in the area, just this single solitary wire…I can send a photo

Bing, can you explain in layman’s terms how I’d begin to chase a draw? I’m fairly handy with electronics so I understand the basics, but I haven’t done auto-electrical in 20 years +

Forgot to tell you the battery tested good at Auto Zone.,

It may be your battery is fine, and that broken wire you discovered connects [or should if it weren’t broken] the engine ground to the chassis ground. Without that engine to chassis ground connection the current path for the starter motor has to go through the transmission and the cv joints instead of that wire , which can cause a no crank condition. It could also damage the transmission and cv joints, since that current is often over 100 amps.

If the problem isn’t that, then you have a simple no crank problem. Very common this time of the year as the ambient temperature is cooling rapidly, which adversely affects the battery performance. Where I start with this problem is to remove the battery from the car, and charge it 24 hours with a battery charger, at the 2 amp rate. That should bring it to a fully charged state. Then have a battery load test done. That will tell you if the battery is still good or not.

Assuming the battery is good and fully charged, or you’ve purchased a new battery, install it back into the car and see if it will crank the engine now.

1 Like

The broken wire is a ground wire and it may be very important for keeping a battery charged. A part-time ground isn’t good for any electrical part. If the main engine to body ground wire is broken, the battery will be almost charged and weird electrical problems will happen such as a slow starter and slow electric windows. On some cars you turn on the AC and the engine would stall 1974 Corolla with bad ground.
After looking at the picture I don’t know where that wire goes.

1 Like

If they couldn’t get a reading at the battery cables but got a reading at the battery itself, then there was corrosion between the battery and the post. just taking the cables on and off may have remover enough corrosion to work but if it was mine I would take the cables off and remove all the corrosion.

As others have said, any wire bolted directly to the bare block has to be a ground wire. I had an Olds Intrigue and had no end of ground problems, partly due to the battery cable grounding directly under the battery with a 10 mm bolt into the inner fender sheet metal. I finally solved the problems with a ground cable from the battery to the engine block and for good measure I ran another one between the block and the fender. Not right next to the battery where the fumes are.


It is very unlikely that a McParts’ store clerk would have any insight into the operation of an automobile charging system. They have a few minutes training to connect and operate ‘space cadet’ gizmos that are supposed to reveal problems but those impressive looking diagnostic tools are more limited in their abilities than the clerk. As is so often the case an accurate wiring schematic and someone familiar with reading one and using test equipment is needed.

Here is the broken wire

Can I just splice this and loosen the bolt, slap it back on (after I bare some of the wire)

but it tested ok

see the photo of the random broken wire I found mounted to the block

Can I just clean that wire up, bare some of the wire and put it back behind the bolt? If I didn’t say, the Aurora has the actual battery under the backseat (it’s enormous), but I too believe this to be a ground for it under the hood,

You’re going to have to get some local help on that. Not possible to diagnose a loose wire problem remotely. That wire doesn’t look robust enough to me to be part of the main battery/starting circuit. But if you are 100% sure where that wire is supposed to go at each end, then yes you could strip the insulation, scrape away any rust/oxidation where it bolts to, so you have shiny metal to shiny metal connection, and re-tighten the bolt with the wire under it to hold it in place. Normally you’d solder on a ring that the bolt would go through, but it can be done with bare copper, a bolt and large enough washer. If you need to splice another wire segment to that wire to make it long enough to reach, do that by direct soldering, not crimping. And make sure the wire you use is the same or larger diameter and same type.

Hey George, the wire has enough room to scrape clean contact, and I am sure where it goes (you can clearly see where it broke off), I’m guessing it’s an important ground as it’s the only wire anywhere near any other wire, and it’s situated right on the block near the serpentine belt, the other end disappears under the manilfold cover so I can’t tell where the other end is mounted…I did recently have my intake manifold replaced if that’s of value
Thanks G