1993 325i Won't Start

[Roadie444]

I went out driving the other day, it started fine when I left, but when I turned it off to go into a store and came back it wouldn't start. It was clicking like the battery was dead, but I had been driving for almost an hour. I got a boost from my friend and when I got home, it wouldn't start again. I took it out the next day and it would always start with a boost, but never on it's own. It also stopped clicking when I tried to start it. I pulled out the multi meter and the battery had 11 volts, but it still wouldn't start. I also went from the alternator to the positive post under the hood (I was told this would tell me if the alternator were working) and it read 11 volts as well. If the battery and the alternator are working, how come it won't even turn over?

[E36328Coupe]

I went out driving the other day, it started fine when I left, but when I turned it off to go into a store and came back it wouldn't start. It was clicking like the battery was dead, but I had been driving for almost an hour. I got a boost from my friend and when I got home, it wouldn't start again. I took it out the next day and it would always start with a boost, but never on it's own. It also stopped clicking when I tried to start it. I pulled out the multi meter and the battery had 11 volts, but it still wouldn't start.I would expect it to start at that BUT it also has to have enough AH stored to have the capacity to crank it


I also went from the alternator to the positive post under the hood (I was told this would tell me if the alternator were working) and it read 11 volts as well. If the battery and the alternator are working, how come it won't even turn over?That only tells you battery voltage, if it rose to around 14 / 14.4 when running that is indicative of charging but really you need to measure the amp output which required more than a little multimeter.

Basically it sounds to me like the battery is not retaining a charge or the alternator is partially failed or failing. A good alternator will puch the voltage up to around 13.8 / 14.4 when running without loads of accessories and lights draining it.

If you have the 18 button OBC you can see this from the drivers seat without a voltmeter

[Roadie444]

If you have the 18 button OBC you can see this from the drivers seat without a voltmeter

I do. How can I find this exactly?

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Also, if my battery has 11-12 volts, wouldn't that mean it is retaining a charge?

[E36328Coupe]

Make sure time and date are set properly before starting as you need that info to unlock the OBC before some of the tests can be accessed unless, of course, volts is one of the ones that can be accessed while locked

http://www.bmwe36blog.com/bmw-on-board-computer-obd-secrets.html


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Also, if my battery has 11-12 volts, wouldn't that mean it is retaining a charge?
If it starts with a jump and doesn't start after a run then either it is not getting charged or not holding enough (or really poor connections from battery to starter, kinda depends if you are jumping it at the rear, or at the front which if leads are thick enough then the car battery becomes irrelevant.).

Now loose or corroded battery (and earth) terminals and earth straps could stop an otherwise good battery charging because the resistance in the connections would mean it can't charge properly and would also explain if the car is jump started using the terminals under the bonnet why that would easily work.

So if battery lead properly clean and secured both ends (and from jump point to starter) and the earth lead in boot (both ends) and earth strap on engine (both ends) are all good electrical connections and the alternator wiring in good order then it's not charging or not holding charge.

Connections that are seldom messed with seldom go bad but can. You can save some potentially wasted money by making sure all connections are good first.

[Roadie444]

Make sure time and date are set properly before starting as you need that info to unlock the OBC before some of the tests can be accessed unless, of course, volts is one of the ones that can be accessed while locked

http://www.bmwe36blog.com/bmw-on-board-computer-obd-secrets.html


- - - Updated - - -


If it starts with a jump and doesn't start after a run then either it is not getting charged or not holding enough (or really poor connections from battery to starter, kinda depends if you are jumping it at the rear, or at the front which if leads are thick enough then the car battery becomes irrelevant.).

Now loose or corroded battery (and earth) terminals and earth straps could stop an otherwise good battery charging because the resistance in the connections would mean it can't charge properly and would also explain if the car is jump started using the terminals under the bonnet why that would easily work.

So if battery lead properly clean and secured both ends (and from jump point to starter) and the earth lead in boot (both ends) and earth strap on engine (both ends) are all good electrical connections and the alternator wiring in good order then it's not charging or not holding charge.

Connections that are seldom messed with seldom go bad but can. You can save some potentially wasted money by making sure all connections are good first.
I checked and it is reading at 11.69 volts

[E36328Coupe]

I checked and it is reading at 11.69 volts
What is and measured where?

And how did you jump start or "boost" the car exactly?

[Roadie444]

Through the obc I got the number. I jump started it with another car, positive on my positive post under the hood and negative on a piece if metal

[spyderg0d]

Any altinator should read like 13 somthing volts. Your battery should hold atleast 12.4 that a starter takes to start. Ei.

Your altinator is bad. Or some part of your altinator.

[E36328Coupe]

Through the obc I got the number. I jump started it with another car, positive on my positive post under the hood and negative on a piece if metalif you measured 11.69 with it running that is not only low but unlikely to be loose terminals to the battery (at least) and looks like a bad alternator, but you can never be 100% sure without knowing if you have proper battery lead and alternator connections and you have not said that they have been checked for security or resistance.

An individual set or windings or diode can go in an alternator and then they do not charge properly but don't put the warning light on either.

I know what my alternator reads when running and battery when running and not and it is not the values in the post above. My old Opel will start with 8V in the battery but it is not volts that cranks our car it is AMPS that do the work and the fact that your voltage is reasonable (I know my 328 will start will 11 on the OBC) is what makes me doubt connections.

[Roadie444]

if you measured 11.69 with it running that is not only low but unlikely to be loose terminals to the battery (at least) and looks like a bad alternator, but you can never be 100% sure without knowing if you have proper battery lead and alternator connections and you have not said that they have been checked for security or resistance.

An individual set or windings or diode can go in an alternator and then they do not charge properly but don't put the warning light on either.

I know what my alternator reads when running and battery when running and not and it is not the values in the post above. My old Opel will start with 8V in the battery but it is not volts that cranks our car it is AMPS that do the work and the fact that your voltage is reasonable (I know my 328 will start will 11 on the OBC) is what makes me doubt connections.
That was with it off. I didnt have another car to start it with at the time.

[E36328Coupe]

That was with it off. I didnt have another car to start it with at the time.
Let us know when you know what it is running on the OBC, front end jump points and battery

[spyderg0d]

What coupe said. Get voltage readings on the battery when the cars off. Get voltage reading on the battery when the cars on. If possible get a reading of the altinator when the car is on. Be careful. Forget the obc until you can drive your car back to a from b.

[E36328Coupe]

Forget the obc until you can drive your car back to a from b.
I don't see why, it gives a very accurate reading of what the cars electronics is actually seeing. Not a replacement for the others but the guy can at least see realtime how the car is doing as RPM rises / in use. Some alternators on the way out will tail off voltage as RPM rises, some will not charge car at idle / low RPM sufficiently but better as it rises. Reading is usually identical to jump points.

No substitute for an ammeter but very few people have on good for 100+ amps to insert in line