1989 911 Carrera 4

Having a battery drain on my 911. Techs have checked battery teast load, battery circuit, etc. all passed. New alternator. Replaced broken window switches which was told could drain battery. Still dead battery in morning. Anybody have any ideas on what could be causiin this? Appreciate the advice.
Thanks,
John

 

With the car off (since it drains overnight), hook your multi-meter up to the battery, and start pulling fuses until the battery power jumps up to full. Then you will know what circuit contains your short. Then it's just a matter of figuring out *why*.

Did you have this problem before the new alternator?

 

The new alternator was a tech suggestion to solve the problem. that after a new battery was bought as well. He "ran meter in series with battery circuit and removed all fuses and relays. Watched amps, never changed. KOEO amp is .008, well within specs. Found no other drains. Window switches were broken which can cause large drain. Replaced. Alternator output at 138 volts KOEO drain=.008 amps." Windows still work with key out of ignition. And occassionally the ding ding ding you get when you open door with key in sounds off with key out of ignition.

Will try your suggestions. Anything else u can think of greatly appreciated.

Frustrated in KY.

 

If the windows still operate with the key off and the doors OPEN, then your door switches are bad, not the window switches.

 

Is it true that the switches can drain battery? Found something else. After turning off ignition I could hear humming noise coming from inside dash. In effort to figure it out I pulled fuses. First one I did was for Front Blower Interior. It stopped. Everytime I started and turned off that humming noise continued till I pulled the fuse. The blower was turned off on the dash the whole time.

Any ideas on if this could be drain and/or how to repair?

Thanks much for the help.

Frustrated in KY

 

Yes that could be part of your drain as well. If the switches are bad, they will continue to give power to various parts of the car, such as the windows. Even though you are not rolling the windows up and down, it will still drain the battery.

For the blower humming, I would turn the car off, wait 5-10 minutes and see if it has shut off by then.Something may be on a timed circuit.