Charging System Failure

[seanrw]

Just wondering if anybody can shed any light on a slight issue I'm having with my 2004 E85 Z4 3.0. I've tried going through the forums etc. and I cannot find anything helpful. I'll try keep this brief:

So I'm driving and suddenly the dashboard lit up like a christmas tree (proper bm ) so I decided to turn back home; I noticed the steering was heavy and the electrical system failing - common alternator failure from experience. A test with a multimeter suggested a faulty alternator as the battery was getting less than 12v. I replaced the alternator and test drove for 30 miles and all seemed ok. Then the next morning the exact same problem returned, dashboard lights etc.

After a lot of head scratching I decided to replace the alternator AGAIN, except the battery is getting less than 12v once started. I have tried an alternative battery to double check but still getting 12v. If I test the live terminal on the alternator its getting around 14v.

So my question is:

If I have a WORKING alternator and battery, why is it not charging? It's as though there's a break in the circuit from the alternator to the battery.

Many thanks in advance!

 

[Zoomer]

I think the Z4 has an intelligent alternator as there is an extra cable to it. I think that this may be not " telling " the alternator to charge the battery , and so the alternator / regulator is not sending charge to the battery. Don't take this as gospel, please investigate it yourself, but I would get the alternator checked out , as most alternator repair shops will be able to bypass this signal from the car.

 

[Hannes du randt]

Dit you get your problem fixed .....the extra wire going to alternator is the obd2 port wire. With my problem i had a long search regarding problems look like most z4 has the same problems. . Alternator not charging . Starter clicking and battery bad , when you test all of these,