Electrical woes, dash lights remain on when ignition is off!

[leicesterboy15]

I've done a search but not found anything the same although it seems like a bad module or ground according to the posts but I don't know where to start.

When I got in the car today I noticed the oil, parking btake and battery light were all on even without the keys in the ignition, when I turn the key to ignition 1 random things happen, the OBC flickers on and off (the one next to the radio, not the dash display), the ac comes on, the rev counter rises then falls and the aforementioned lights flicker. When I go to ignition 2 normality is restored, the car starts fine and everything behaves itself when the car is on. As I'm turning it on and off to test the above symptoms are intermittent and I can hear clicking from what seems like the ecu area.

When I got to the gym the 3 symptoms seemed to subside slightly and I was left with the 3 dash lights (brake, oil and battery) glowing at random levels of brightness, sometimes dim, sometimes bright.

When I got home there were no problems at all, although I suspect it will be back. Its been really hot here recently (well hot for London!) and it rained today, this is the only cause I can think of, when it rains I also get the brake, plate and dip beam warning so could this be related? Am I barking up the wrong tree? Where should I start looking? Its a bit disconcerting, the one thing in life you can usually rely on is when you take the key out of the ignition the car is off :)

I hate electrical problems!

[bubba966]

Sounds like a low voltage type of problem. Either from the alternator on it's way out and not properly charging the battery, or the battery is dieing. Any idea of the age of the battery or alternator?

[shogun]

low voltage problem. check battery and alternator. Unlock OBC and check also while driving with # 9 test

[leicesterboy15]

I replaced the battery last year with a good bosch one but have no idea about the alternator, its probably the original. The stereo also switches off if I turn the volume up, I thought this was a bad earth but could it be related?

[shogun]

It does not matter how old a battery is, that can always happen. Checking the battery and the alternator voltage will give you the answer. And the battery has to be checked under load, all other simple testing is meaningless.

a voltage regulator is good when the reading hardly reacts to change of engine speed or to adding power consumers like electric window heaters or main headlights.
Here is what aboutcom.autorepair tells us: (excerpts)

The alternator produces electricity and delivers this electricity to the battery and maintains a full charge at all times. If the voltage produced by the alternator goes above 13.5 - 14.5 volts, the battery will be ruined very quickly. It's the job of the voltage regulator to keep the output voltage between the 13.5 - 14.5 volt range.

Okay, now that we have a DC current that the car can use, we need a way to control that current. That is the job of the voltage regulator. As the name implies, it regulates the voltage going to the battery. It does this by turning current to the field (stator) terminal of the alternator on and off. If the battery voltage goes below 13.5 volts, the voltage regulator sends current to the field terminal and allows the alternator to start charging. Current will then flow into the battery and bring it up to full charge. If the voltage goes above 14.5 volts, the voltage regulator shuts off the current to the field terminal and keeps the battery from overcharging and cooking itself. This is how the voltage regulator controls the alternator output.

When you first start your car, the alternator needs some current to start working. The voltage regulator supplies this current to the field (stator) terminal of the alternator to get it started.

So far, all we have talked about is voltage. Now we'll discuss the amperage output of the alternator. The state of charge of the battery controls amperage output. When the battery has a full charge, the electro-motive force of the voltage lowers the amperage to almost zero. As the battery charge wears down, the electro-motive force is not enough to stop the amperage, so it flows into the battery and charges it again.

As you use more electrical accessories, such as lights, heater etc., the electro-motive force decreases and more amperage flows into the battery to compensate for the added load. It is extremely important that when alternator efficiency is checked, both voltage and amperage outputs are checked. Each alternator has a rated amperage output depending on the electrical requirements of the vehicle.

Testing the alternator is simple and basic. You need to check the voltage and amperage output. The voltage is easy enough to check with a voltmeter. If the voltage is between 13.5 and 14.5, it's a good bet the alternator is good. To check the amperage output, you'll need some special equipment. You'll need an ammeter and a load tester to check the amperage.

When the alternator is load tested, a simulated load, usually ½ the Cold Cranking Amperage rating of the battery is applied to the charging system. Then the engine is run at 2200 to 2500 rpm and the amperage is read on the ammeter. The reading should be close to or at the rated amperage of the alternator. If it is, then it's good. If it's substantially lower, then it is weak and should be replaced.

There are some signs you can look for that will indicate a problem with the charging system. If the headlights brighten or the blower motor picks up speed when you rev the engine, you may have a weak battery. This indicates the battery may not be holding enough current to run the car and is working off the alternator. If the charge light is on dimly at idle, this could indicate a weak alternator. If all the warning lights come on while driving, this could indicate a bad diode pack in the alternator. It may or may not still be charging, but you don't know unless you have it checked. At any rate, it will need to be replaced.
http://www.bimmerboard.com/forums/posts/652362/
how to test video
http://www.bimmerboard.com/forums/posts/622924/

[bmwrp8]

had similar problem like your before. Have your alternator checked. And the connections of the alt.

[leicesterboy15]

OK thanks guys, the problem hasn't happened again since that day but I ran test 9 as recommended above and it read 14 - 14.15 on idle at start up, then with lights, radio and fan on it ranges from 12.3 - 13.7, when I am at idle after the car has warmed up with all the bits running it remains at around 13.5, at idle with all the bits off it stays at around 14.08.

Is that conclusive or just more confusing?

I suspect whatever it is will happen again at the worst possible time so I still want to diagnose it.

[whiskychaser]

Just for comparison this is what I got:
Idle cold/normal temp: 13.93/13.85v
Idle cold/normal temp: with headlights, radio and fan (stage 1): 13.77/13.69v
And for luck:
Idle cold/normal temp: with headlights,radio,fan,HRW & aircon: 13.69/13.62v
The OBC scrolls a little so I'm giving the figures it locks onto most.
The battery is about a year old but the car hasnt run for 3 days and then it only did about 14 miles. Before that it probably hadnt run for a week.

PS I was betting on a duff alternator diode:D

[tim eh?]

Those are really weird symptoms! Do you have an alarm system? maybe something making intermittent contact around the ignition switch?

Next time it happens you could pull fuses until the dash lights go off and you might be able to better isolate which circuit the problem is on... (shrug?)

[Ross]

OK thanks guys, the problem hasn't happened again since that day but I ran test 9 as recommended above and it read 14 - 14.15 on idle at start up, then with lights, radio and fan on it ranges from 12.3 - 13.7, when I am at idle after the car has warmed up with all the bits running it remains at around 13.5, at idle with all the bits off it stays at around 14.08.

Is that conclusive or just more confusing?

I suspect whatever it is will happen again at the worst possible time so I still want to diagnose it.
The 12.3 tells me you have a charging problem. The glowing battery light is probably because of a bad regulator diode. I'd start with a new regulator, it's far cheaper then an entire alternator and is usually the culprit. Easy to change too.