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Steve
Steve, BMW Expert
Category: BMW
Satisfied Customers: 24123
Experience:  BMW Expert
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I have a 1998 E38 728i, first of all the phone stopped

Resolved Question:

I have a 1998 E38 728i, first of all the phone stopped working, didn't think much of it as didn't use it anyway, but in the last few days my wipers have stopped working, the sat nav and whole computer system has frozen, radio doesn't work, putting car in reverse doesn't adjust passenger mirror for parking and internal lights come on and off on their own, its had an hours diagnostics at a specialist with no solution other than to change battery which is at 11.2 volts but garage don't assure me that this will solve everything. Could it be anything else?
Read that it could be a fault draining the battery so don't want to rush into changing it if it is something else.
Submitted: 2 years ago.
Category: BMW
Expert:  Steve replied 2 years ago.
What is voltage with the engine on?
Customer: replied 2 years ago.
Hi,
It was running at 13 with engine running,
Thanks
Expert:  Steve replied 2 years ago.

I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.

13V while running is too low, as is 11V at the battery.

you definitely have an alternator and/or battery problem which should be addressed as voltage issues are very common to cause electrical problems

as far as other causes, a failed ignition switch, bad ground or failed control module somewhere on the car can also cause similar issues, but I would first resolve the obvious voltage issue which exists based on the readings you have provided.

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 2 years ago.
Many thanks for that, we put a new battery on it yesterday and it worked for a bit, got in it this morning and it's got all the faults as before and now te brake lights are constantly on. Do you think we should go down the alternator route now?
Expert:  Steve replied 2 years ago.
If the running voltage is still 13v, yes.
As the question has been answered, please kindly CLICK ON a positive rating. Thank you.
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