I think she's dead jim....zero electrical after car shut off randomly

[ar393]

Car is a B6 V6 6MT quattro avant, 235K miles

So I was out of town for two weeks. Car was sitting in my driveway the entire time. I come home and go to start my car and I get nothing. I check and my crappy bluetooth OBD reader (different from my ross tech) was still plugged in, so im thinking that might have drained the battery.

I check the battery with a meter and its dead. I try my trickle charger, and the battery is too dead for that to work. I get my friends 15-amp charger/starter, hook it up and I get some electrical response after about an hour. I get the usual clicking of a very low battery. I switch the charger to starter mode; turn the key and she started right up.

I disconnect the starter/charger, close the hood and go inside for a few minutes to grab some stuff, I hear the revs go up and down a little bit (which isn't too out of whack since I have a hole in the exhaust, not like it redlined or something, but maybe swung from 500-900 instead of sitting at 750) ....then I hear NOTHING. I go back outside, and the car is off with the key in the run position still. I go to try the key and I get zero electrical response again, try the hazards, and nothing.

I go to pop the hood and put my meter on the battery, and there is very light smoke of some sort in the engine bay. Like electrical fire type smoke (im a volunteer firefighter). I instinctually go to disconnect the batter and the battery cables are WARM to the touch. I pull the battery completely, take it out, multimeter shows some life in the battery and so I put it on my trickle charger overnight. overnight it charges fine, I test it the meter and get good voltage. I connect the battery with a set of jumper cables instead of fighting to get it back in its spot, I turn the key, and get nothing. I hit the hazards, I get nothing. when i go to disconnect the jumper cables, they are WARM too. The smoke didn't come from the driver's side a pillar where the ECU/computer is, but from around and under the motor. after a day or so I could still smell the smoke and it was strongest at the air manifold, but also I was limited to where I could put my nose.

thoughts?

[Kevin C]

My guess is an age deteriorated cable that failed under load as the alternator tried to charge the battery at a high rate for an extended period. I would pull the battery cables and start checking each cable back to the alternator /engine block with an ohm meter. It sounds like a complete break on either the ground or the hot side. Cables work harden from flexing and eventually can break internally, some strands are overlapping and some may not have fully broken. Under load the extra resistance from this deterioration causes self heating, that increases resistance and then it goes poof. Areas with road salt are more likely to have this. Likely failure points are where the jacket is cut back for connectors such as a chassis ground.

[ar393]

If the cables were broken, the battery cables shouldn't get warm to the touch, because no current is going through them, right? If it's warm doesn't that imply that there is a lot of current going through them?

Yes this car has and does see road salt (northern NY and New england). I am horrible with electrical work, arg.

But I will try and take a look under the car and check by the alternator/starter, I could see smoke from that area being the source of the light smoke I saw. wouldnt the hazards still work if one of those cables to the engine bay was toast?

I am getting ZERO power in the car at all. nothing, like there is no battery, even though there is.

[Kevin C]

Warmth does indicate current flow that still does not mean that somewhere a cable may have failed (or partially failed). Your description sounds like a total failure so its seems likely that you have a complete break somewhere. If cable to the starter is still OK but it has break (or has high resistance) to the alternator the car wont charge. A failure to the alternator and a poor battery will cause problems.

Start by eliminating easy and obvious parts.

Does your battery have any voltage under load after you charge it and connect it? Put a volt meter on it and try and crank it over. If it stays above 12V and does not crank you have another problem. Connecting the battery using a long set of jumper cables may create a new problem. Jumpers are often design to only assist and may have too much of a voltage drop to start the car.

If you can smell a smoked part it makes sense to dig into that area and see what charred. The alternator needs a low resistance connection to the battery to work. Cable heating is the current squared times the resistance. If the alternator is trying to charge at 15 amps and you have just .25 ohms of resistance in the cable the heating is 15*15*.5=56 watts. Half an ohm at 20 amps? 20*20*.5=200 watts. Small resistances can cause significant heating.

Voltage drop is the current times the resistance. Using your .25 ohm figure, if your car is drawing 30 amps 30*.25= 7.5V. The alternator measure system voltage internally at the alternator. Cold it will set a voltage of about 14V. If the car is drawing 20 amps of current and has a slightly bad cable you get this: 20A * .25 ohms= 5 volts. Since the alternator is internally set to 14 volts, all you get at the battery is 14V-5V=9V That is not going to run the car very well. The cable heating at the high resistance point will be the current squared time the resistance. 20*20*.25= 100X. That will burn a section of cable up.

FYI, A set of 20' 8 AWG jumper cables will have a resistance of about .013 ohms. If your battery is totally dead and you try and crank the motor over it might look like this assuming (300 Amps cranking current). The impedance of the starter circuit would be about 12V/ 300A= .04 Ohms. If you now add the resistance of a set of jumper cable: .04 ohms + .013 - .053 ohms. 300 amps becomes 226 amps ( assuming back emf is constant).

The voltage at the starter would be 226A * .04 Ohms = 9V. The voltage drop across the cable will be : 226A * .013hms = 2.9 Volts. That assumes the battery voltage does not drop. Basically some jumper cable sets do not have low enough resistance to jump start a car with a totally dead or absent battery.

[ar393]

Start by eliminating easy and obvious parts.

Does your battery have any voltage under load after you charge it and connect it? Put a volt meter on it and try and crank it over. If it stays above 12V and does not crank you have another problem. Connecting the battery using a long set of jumper cables may create a new problem. Jumpers are often design to only assist and may have too much of a voltage drop to start the car.

If you can smell a smoked part it makes sense to dig into that area and see what charred.

Just FYI the problem and story above happened about a week ago. I just wasnt able to get around to looking at it at all until now

UPDATE

So after a week, on a whim I was like let me go and put the battery in again and see what happens. I reinstall the battery fully, wait a bit, no smells. Multimeter read above 13 before I reinstalled it.

I go and open the car door, and suddenly the car responding like it should. Hazards work, lights work....wtf....

I go and smell around the engine bay, no smells. I turn the key to the on position. everything is acting normal. radio works. still no smell coming from the engine bay.

I go to start it.....nothing. hmmmm. thinking about where the smoke was most seen, and zero happening even though there is power, im thinking the starter burnt out? The starter was replaced about 15 months ago, unfortunately that mechanic closed shop and moved to the west coast, so I can't go back to him.*

Is there an easy way to test the starter? is there a safe way to put 12 volts to it directly? Where would that be if its possible?

Could a messed up alternator and/or starter "killed the car"?

So one other thing. About a month and a half ago, the SAI pump would stay on a lot longer than it should....like 15-20 minutes and not 2 minutes. I did not find information or solutions after reading and posting as well. I believe all of those things are in the same "neighborhood" Could that have fried and then knocked out the starter?

[Kevin C]

Put a meter on the battery and try and crank it. Does the voltage drop under 10V?

If yes: You probably need a battery.

If No you may have a bad starter or cable to the starter.

Clip a volt meter to the large terminal on the starter and the other end to the engine block. Does it read full battery voltage?

If no you have a bad cable.

If yes try cranking the engine over.

Does the voltage drop to close to 0 with no cranking?

If yes you have a bad connection to the starter (cable, terminal etc.).

If no check to see if power is being applied to the small terminal when you crank the motor over.

If yes you probably have a bad starter.

Or get it towed and have a shop check it out. Based on the previous info you have a burnt cable and the problem was compounded by testing with a very discharged battery and using jumper cables to connect it.

Run the tests and or look for what smoked. I doubt your starter coincidently failed at the same time, most likely its a wiring problem.

[ar393]

Thanks, I will try this and see what I can figure out today before it gets dark or I'll have to try it in the morning.

any thoughts on if the SAI pump burnt that something else could have caused this or caused other things to go wrong?

[ar393]

So the thing that gets me so confused as to what happened, when it was originally running, and it turned off...why did it turn off, and when it did, what caused me to not even be able to flip the hazards on? could the battery have been fully drained during that time? wouldnt my alternator been charging my battery while it was running (my limited understanding a few minutes at idle would add only a minimal charge)?


I may need to borrow a friend's meter or leads.

[Kevin C]

So the thing that gets me so confused as to what happened, when it was originally running, and it turned off...why did it turn off, and when it did, what caused me to not even be able to flip the hazards on? could the battery have been fully drained during that time? wouldnt my alternator been charging my battery while it was running (my limited understanding a few minutes at idle would add only a minimal charge)?


I may need to borrow a friend's meter or leads.

If the cable that failed is from the alternator then the alternator would stop supplying power. Your car is then running off of the battery. It sounds like your battery was just barely charged, and then the battery became completely discharge. It takes a long time to recharge a battery and yours could also be marginal. Without power, the fuel pump and ignition would no longer work. Or you have a bunch of water in your ECU box and stuff is randomly shorting out. Start simple, look and check the easy stuff. A test meter is not that expensive. You don't need super fancy, just basics ohms and volts.

[ar393]

Does the voltage drop to close to 0 with no cranking?

If yes you have a bad connection to the starter (cable, terminal etc.).

If no check to see if power is being applied to the small terminal when you crank the motor over.

If yes you probably have a bad starter.

I would test that by going from the small terminal to a ground (block or ground point?) and if I see voltage when the motor is cranking that means power is getting through the starter, but the starter isnt working.

[ar393]

If the cable that failed is from the alternator then the alternator would stop supplying power. Your car is then running off of the battery. It sounds like your battery was just barely charged, and then the battery became completely discharge. It takes a long time to recharge a battery and yours could also be marginal. Without power, the fuel pump and ignition would no longer work. Or you have a bunch of water in your ECU box and stuff is randomly shorting out. Start simple, look and check the easy stuff. A test meter is not that expensive. You don't need super fancy, just basics ohms and volts.

Man, I can't thank you enough for all this info. I have a basic, cheap, digital one, and an older analog one that I trust more.

I just don't have long enough leads or leads with clips. I am pretty sure one of my friends does though.

Just to make sure here, and sorry I if I am asking stupid things or whatnot, If a fully charged battery was installed, if the starter was working and getting power, it should crank and run for a little bit? regardless of the status of the alternator?

Now that I am getting power, is there anything that I can scan or test with the VAGCOM from rosstech?

[Kevin C]

I would test that by going from the small terminal to a ground (block or ground point?) and if I see voltage when the motor is cranking that means power is getting through the starter, but the starter isnt working.

Clip a volt meter to the large terminal on the starter and the other end to the engine block. Does it read full battery voltage?

If no you have a bad cable.


Keeping the volt meter connected to the large terminal on the starter and the other end to the engine block.

Try cranking the engine over.

Does the voltage drop to close to 0 but the motor does not crank?

If yes you have a bad connection to the starter (cable, terminal etc.).

If no check to see if power is being applied to the small terminal when you crank the motor over.

Do you get power to the small terminal when you try and crank it over?

If yes you probably have a bad starter.

Also...



You can get really long leads for a meter or you can have a friend help.

[ar393]

Tomorrow I plan on doing all of the things you've clearly laid out for me. I can't thank you enough for the info.

Please bear with me with this thought, this is not saying the battery, alternator, cabling, or combination of them is not the problem:

So i briefly mentioned that the SAI pump had been acting very weird once the weather got cooler this year. it would stay on for like 15 or 20 minutes instead of 2. The first time I found this out I had gone on a short trip after having gone on a long one. On the long trip the SAI pump had enough time to turn off (someone has suggested in another thread that there may be water in the ECU box which was a problem with this car in the past with one of its previous owners, so that still has to be re-checked). On the short trip, when i turned the car off, I heard a very strange noise, like a high whine. It was the SAI pump still running even though the car was off and the keys were not in the ignition. I tried to turn it back on, but the car wouldn't turn over. Everything else worked, but it wouldn't turn over and the pump wouldn't stop running. My only solution was to disconnect the battery and the pump stopped. I reconnected the battery and went about my business. I came back out to the car and it started just fine. I did a few tests and all I could figure out that the SAI pump ran a lot longer than it should have before turning off. Each time I was on a short trip, I had to disconnect the battery (I understand now that the relay for this is under the ECU, so I couldn't just pull it, even though I pulled every fuse in the side panel at first and it kept running) to turn the thing off and so I could restart the car, or I would have to leave the car running until the SAI pump shut off, then I could turn the car off and know it would start again. In my limited knowledge and also I have asked about to a couple shops when it first happened, everyone told me that the SAI pump is going to burn out if this keeps up. The SAI pump is near the starter on this engine (3.0 V6) if I am not mistaken.

Could a fried SAI pump that is acting like it's on (completing the circuit), make my car not start like described above? and that would also put a good draw on the battery too right? This excess draw, along with either (or both) a shitty battery or alternator, would then drain the battery quickly while it was running in my driveway and then as you stated earlier, cause the car to longer have enough power to run, so it died?

I do have a picture from when I first got the car and had the ECU box open, and you could see at some point there had been some serious water intrusion. I should be able to post it here if I can find it.

[Fast4esT]

Sounds like the battery is pretty old. I agree with testing everything mentioned but if the battery can’t supply enough power to crank or start the car you can be chasing circles. Test the battery on cranking I agree.

[ar393]

Put a meter on the battery and try and crank it. Does the voltage drop under 10V?

Battery read 13.55 on my digital and analog meters before anything was tried. There was no big drop when car was cranked.

If No you may have a bad starter or cable to the starter.

Clip a volt meter to the large terminal on the starter and the other end to the engine block. Does it read full battery voltage?

Clipped a connection to the large terminal and the other end to the grounding point above the SAI pump.
Tested ground point with meter from battery and it read full battery voltage.
They read around 12/12.5 from the big terminal.

If yes try cranking the engine over.

Does the voltage drop to close to 0 with no cranking?

no big voltage drop when attempting to start.

If no check to see if power is being applied to the small terminal when you crank the motor over.

once connected to the small terminal (surprisingly easier than the large terminal) and no key in the ignition, the digital meter read 9, analog meter read about 2.5.

no change when attempting to start car.

I no longer have a spare pigtail to try to apply power directly to the SAI pump to see if that is toast, nor do I have spare 373 or 219 relays and there are no more salvage yards around me that let you go pull shit. So if you guys have any, let me know.
I am not sure if its safe/smart to apply power directly to the starter either.

would I be able to turn on/test the SAI pump on using VAGCOM/VCDS?

I tried my theory of disconnecting the SAI pump to see if that did anything and it did not. So this leads me to think that the starter is toast (I dont know why that would have kept running when the car was idling to burn out) and that the SAI issue is completely separate. Do you agree?

This starter was only installed less than 15 months ago......god damn it.

Or get it towed and have a shop check it out.

Every shop around me is booked into december already. my job starts tuesday.

[ar393]

Sounds like the battery is pretty old.

Battery is from 4/21, barely 19 months old.

I agree with testing everything mentioned but if the battery can’t supply enough power to crank or start the car you can be chasing circles. Test the battery on cranking I agree.

I don't even get the click click click of attempting to crank with a weak battery.

I will test it right now with a jump pack. No crank with jump pack. Putting jump pack on the charger too just to eliminate any possibility that it didn't have enough power either.

Even after all this testing, battery still reads above 12 with both meters.

[Turbo510]

Something drained your battery, made a burning smell low in the compartment. I would suspect the alternator until proven otherwise. Disconnect the battery positive (and the smaller cable from the fusible link) and check for continuity between the large red cable and ground. Should be an open circuit.