Morning All,

I have a 2004 645ci that only has 50k mileage on it and is in generally very good condition. (I drove it to Germany last summer without any issues)

Recently though I have been getting a host of error messages flash up (Dynamic Drive fault, power steering etc) When this happens I lose power steering and gearbox becomes very clunky and wont change above 3rd (this happens soon after start-up)

I have had all these errors cleared with a local mechanic but looking for a specialist to diagnose whats causing it and maybe it needs its "brain" replaced as I hear this is a common problem in these older cars where the tech was very new at the time.

Many Thanks

Karl

Afternoon Karl

Welcome to the Forum

There is a Register of BMW Specialists Google/Siri  will help you should be able to locate one not to far away from you.

Before spending your hard earned here are a few of things to check (1) Check Battery Voltage at the charging points under the Bonnet engine off,  it should be 12.5v anything below that indicates a failing battery which can cause all your issues. (2) Check the Voltage at the Charging Points engine running voltage should be 14.5 + Volts anything lower points to an Alternator/Voltage Regulator issue (3) BMW love multiple earth points the mounting for these can often become corroded check earth continuity or simply undo the mounting bolt clean everything apply electrical contact cleaner and bolt it back

Reset all Fault Codes and check to see if any come back

Dave

Fantastic advice many thanks Dave

I checked the battery yesterday and it was around 11 so definitely an issue there. I have put it on drip charge and will try and get it back up to correct levels. Its a relatively new battery so maybe its just the cold weather - although did drive the car 100 miles to Somerset and back over the weekend so would have thought it would be fully charged. Potentially that suggests an alternator problem?

Thanks again

Karl

Morning Karl

11v is a dead or dying battery, if you drove to Somerset it should charge the battery OK the issue is the Battery doesn't seem to be holding the charge. My bet would be duff cell in the battery.

The battery inmy E53 4.6is died suddenly 3 years ago the date stamp said it was the original battery (2003) 18 years old The replacement from ECP came with a 5 year warranty but had to be replaced (under Warranty) last year. (Touches wood) the battery in the E70 was replaced 5 years ago and is still going strong. So even though the battery change seems recent it could still die on you

Dave

 

Hi … I second @Greydog sounds like a dead battery cell. 
it’s amazing what a small amount of under current on the battery does to the brains of the car. 
I got a new battery from euro car parts on offer for £80.

my Halfords one was a yuasa one I believe and was £114. It lasted around 2 years, before I started to notice random faults appearing. The garage tested the battery and said it was ok, just needed a good run out, but I took it out and it discharged by itself.

Stu. 

Karl… if the alternator fails, your car will run for about 10 miles before dying…. I can assure you this has happened to me!

Hi all,

 

Thank you for all the replies.

I took it in to get the battery checked as its still under warranty and there's nothing wrong with the battery (and the alternator is producing the correct current)

Issue seems to be, with the freezing weather recently, there was a build up of moisture in the area below the battery in the boot. Mechanic says he thinks the charge coming from the alternator is not all reaching the battery. There is a control unit next to the battery he says he thinks is wet/damp. He's going to take it all out tomorrow and report back. I have put towels and paper towels down there to absorb as much as possible overnight. I let you all know what we find tomorrow 

 

 

Morning Karl

My money is still on the battery, simple test disconnect the battery fully charge it and leave it overnight if it looses charge that will confirm it

The control unit by the battery is probably the PDC module. Water in the area doesn't help check the floor drains are not blocked (I guess your mechanic will do that)

You could also check for a prasitic drain on the battery, battery fully charged car closed apart from the bonnet, let the car go to sleep (all systems off the tell tale by the gearshift will go out) then check at the under bonnet charge points for any discharge. There will be a small milli amp discharge clock etc, anything higher will need investigation

Good luck 

Dave

 

Finally cracked the problem!! It turned out to be a faulty alternator as we established that there was nothing wrong with the battery. Replaced it and battery now fully charged and holding charge.  All fault codes reset and staying off!

Thank you for all the replies. This is a fantastic and very helpful forum

Best,

Karl