Weird Problem - Dashboard lights, then won't start...

[subharmonic]

Ok, I'll give you some background.

The car has been running fine all summer, though at one stage the amber engine management light came on, but before I could get it into the garage, the light went out a few days later.
Also, before the summer, we used to have an intermittent problem where a few warning lights would flash on, and then go out a second or two later, after the car had been running for a while - say a quarter of a mile round the block.
All summer, no real issues with this.
However, since the wetter, colder weather has come in, the xmas tree light effect with the warning lights has become increasingly frequent.
Radio has switched off as well, and windscreen wiper performance reduced signigicantly, for a few seconds, and then self righted.

However, today, my girlfriend got about 10 minutes into her journey to work, and she's now broken down, after the usual warning lights on the dashboard flashing.
The lights that would come on are things like the handbrake warning light, I think also the engine management light, the ABS or traction control light, and maybe another one or two things come on, and then go out.

So, any ideas?

Any help really appreciated...

[chefsboss]

Oh my god!. your car is about to explode. GET OUT NOW!!!. (only kidding).. Pal. I am pretty sure you will be shopping for a new battery soon. .but you may get lucky like me, and find that it was only your engine ground cable loose (under the pass side of engine). or possibly another loose cable.
suggested 1st course of attack: Google "E46 OBC hidden codes"
Practice and do the on board voltage test. (the car's running voltage will be displayed on your dash where the MPG or outside temp etc.. is now)
And watch closely (leave it there while running and driving)...
Most likely, you will see the voltage dip way down (in rare cases way up).. just a second or two before you have the Christmas* tree on your dash. And then wammo!.. car will go into failsafe or other scary madness. And then magically be fixed when you re-start it.
Curiously, the battery light is usually dark (due to under-design of the charging system) but if this is the case (and I am quite sure it is).
this will confirm a charging system issue, that usually begins with a fading battery.
What's happening is your car with all its various modules can just barely run with the alternator output... but occasionally with normal power surges etc.. it will have to suck some from the battery (which is acting sort of like a capacitor).. which is usually replaced a little later. ,
but as battery gets older it is not able to store as much juice (although still enough to start the car).. and that's the 1st sign of that. Months before the battery light ever realizes what's going on.
BE forewarned. Don't take it to a shop. They will usually not know of this specific E46 battery as a capacitor issue and try and sell you modules and everything in between.
Good luck!
Of course... I may be wrong. So plaease make sure you post back for future generations of Christmas* tress goers! Cheers!


* Keep Christ in X-Mas!!!

[nathancarter]

I agree - erratic voltage. Things to check, in order of increasing expense and difficulty:

- Loose connections at battery terminals
- Loose connections at alternator
- Battery health (Autozone and Advance will do this for free)
- Alternator output voltage during idle and load (should consistently be about 14 volts)

[Chief Cake]

My money is on the alternator.

[Zchild]

How old is your battery, my money is on the battery...

[subharmonic]

Cheers for the responses - much appreciated.
(And I agree regarding the Christmas comments - my dad wouldn't be please me using the retail friendly shorthand lol).

Anyway...

My gf explained a bit more clearly last night that prior to pulling over, the car didn't just do the christmas tree thing - it also juddered a bit.
I thought she said that the engine was still running, and it was, but she said that the engine wasn't actually driving the wheels.

Now I wasn't there, and I have no practical experience of a car going into "limp" mode, so maybe it was actually driving the wheels, only she was so shocked and shook up by the episode she didn't notice this - I'm not sure.
But certainly, the car did sort of shut down, without the engine cutting.

Roadside assistance guy dismissed thoughts of a dodgy alternator, as when he did his voltage checks etc, he said the batt voltage was as expected, so the alternator was topping up the batts charged ok.

However chefsboss, I think a lot of what you say is ringing bells re the way the car has been behaving.
I have a sneaky feeling the car may be running the same battery as it came with from new. I don't remember us changing it at any time.
So, after 70,000 on the clock, it probably makes sense it could indeed be this...

Supposedly there were 3 main error codes - one of them was 2813.
Not sure what the others were.
Wouldn't mind trying to get something to check these codes myself...

[nathancarter]

Hmm.

I'd give a thorough inspection to the belts and pulleys - if the main accessory serpentine belt breaks, or comes off due to a failed pulley, then the alternator, power steering, and water pump won't be running, and the car will do all sorts of odd things - most notably, overheating.

Hopefully this is not the case, and it's simply a charging system problem. And I would expect that the roadside assistance guy would have at least popped the hood and looked at belts. But, still, give it a quick visual inspection.