E30 Zone

Okay guys heres my problem my car starts fine in the morning then the second time you go to start it its dead as a dodo.

The weird things are that my obc retains the clock memory but my headunit looses all of the station presets and other settings.

I checked the battery after i jump started it and drove round for a bit it was 12.7 volts motor not running and about13.4 - 13.6 running

and this happens only once the seond time you try start it after a drive in the morning then its fine for the rest of the day after a jump start

car is a 325is

sounds like something might be draining you battery over night

Check the light in the boot to make sure it's not on all the time.

Mine started doing this - then eventually died altogether - Tried charging it but the same thing happened - The AA confirmed that the battery was faulty - I changed the battery, problem solved.

Thanks lads will go get new battery start from there

Well drove the car all day no probs at all then decided to go get dinner and it happened went to crank the car over and nothing i have a switchable auto in my car and it was clicking as it always does with a dead battery so went to grab the voltmetre and got 12.2-12.5 volts thouhgt plenty to start the car and gues what it started so is it the ignition switch or simething else but why does my headunit loose all memory but the obc retains it

sounds like a dodgy earth somewhere - battery's getting and holding a charge (a good battery should be around 12.6V, I think) but you're shaking a connection somewhere.

Undo the earth terminal, clean it up and retighten, and if it's not that then either replace that earth strap or start cleaning up the other ones in the engine bay, and the ones on the starter.

Open up your diagnostic socket and identify pins 11 and 14. The next time it refuses to start from the key, use a short piece of wire to link these two pins together, and see if it starts from there.

Use the voltmeter when you have the problem, see if the volt changes when you turn the ignition.
If im not wrong the battery can hold 12 volt all time when low on amps aswell, so when you turn it will drain the battery if it has low amps, then you would get low volt reading.
Other than that it could be faulty wiring somewhere.

To add to the previous post:

The battery is obviously just an energy storage device. The rate at which it delivers the energy is the power output and this is given by the multiplication of the voltage and current. This can be seen as analogous to water, the power in a flow of water is the amount of force behind it multiplied by the amount of water flowing; a fast moving jet wash has a lot of power (high force, low amount of water) and a slow river has a bit more (low force, lots of water). If there is very little energy in it it will obviously not be able to supply much power, if no current is being drawn then 0 Amps * 12 Volts is still less than very little power, so you can expect 12V. As you start to draw current you will find that the voltage drops in proportion to the lack of energy.

thanks for all the help i was gonna start with the wires but i think i might get a new battery while i'm at it it's been there for a while and looks dodgy

Jay07 wrote:Mine started doing this - then eventually died altogether - Tried charging it but the same thing happened - The AA confirmed that the battery was faulty - I changed the battery, problem solved.

Auto Electrician confirmed this for me. Fortunately battery was under warranty and was replaced free of charge.

4

AUS325IS wrote: but i think i might get a new battery........ it looks dodgy

If you can identify a dud battery by looks alone, then you know something I don't!! All the dud batteries I've seen have looked exactly like new ones, apart from a few scratches and dust.
The way to solve a problem is by tests and deduction; not by throwing money at it and changing random parts.
I've described the first test for you to do, but it's your money.....

Brian what effect does shorting those two pins have?

As far as the battery is concerned at least check the level in the cells before binning it.

Shorting these pins will engage the starter motor almost directly, therefore eliminating a considerable amount of car body loom wiring/plugs and sockets/ switches/ relays from the list of suspects.

Ah thanks, that's useful to know. I'll put that in the list of things I'll forget when my car won't start at midnight in the pouring rain.

Brianmoooore wrote:4

AUS325IS wrote: but i think i might get a new battery........ it looks dodgy

If you can identify a dud battery by looks alone, then you know something I don't!! All the dud batteries I've seen have looked exactly like new ones, apart from a few scratches and dust.
The way to solve a problem is by tests and deduction; not by throwing money at it and changing random parts.
I've described the first test for you to do, but it's your money.....

What i meant was that when i open the cell caps to look at the water level its all black inside and the water is murky like the lead from the cells has collapsed perhaps i should have been more clear in earlier posts.

Where can i get a diagram of the diagnostic connector and all the pin numbers it has i'm a bit sketchy doing this test incase i blow the ecu

Hi Aus325i.
If you are in Sydney, send me a PM. I have a spare battery, the wiring diagrams and most parts needed to get you going. Mark

Thanks mark but i'm in melbourne