95 C4 993

After being baffled on my battery issues for several months---wasnt holding a charge that well----I finally went down the Optima Red path this weekend. I think the core issue was my battery is/was 7 years old (Sears Diehard) and I didnt realize the age of the battery until I went through my paperwork. Seven years is probably pushing it for a battery in my opinion. Sometimes I would hear my CD changer just changing for no apparent reason while the car was sitting there and think could have resulted in some earlier battery dying issues. But who knows, will see.

My local Costco had them for $129.99, plus a refund of $9.60 (core) for my old battery.

The cranking power alone on the Optima something that is 5x of what my Diehard battery has been for years.

Now the real question---I wonder why in the heck I have a cable that runs to the positive on the battery that powers my windows? Is there any logical explaination behind this wiring? Take off that cable from the positive, my windows dont work.

Fly911

This is probably for safety, in case the ignition shuts off in a crash, or if you "drown" the car in deep water, the battery will still be able to roll down your windows.

95 C4 993

When the ignition is off, my windows dont go up or down.

Warpig

I installed a DEI power windows module Auto Up/Down on both my power window circuit and my sunroof circuits. Due to the way Porsche wires the 993 both legs of the power window motors have +12V when the car is on but the window switches are in the middle position. when you activate the power window switch it grounds one leg or the other of the power window motor to cause the motor to run. They also have the power window +12V supply switched by a relay in the front fuse panel/relay center. When you turn the key in the Run or accessory position this relay activates and supplies both legs of both motors with +12V. I assume the relay is there to cut the 12V from the window circuit when the car is not "in use" as this would seem to be a safety feature. In order to install my DEI window control module I also had to give the DEI module and thus the window circuit via the module a constant 12V supply from the Battery or the modules would still not be able to operate the windows when the car is off. Lucky the module also switches the 12V supply off the motor legs when the module is not operating. Knowing all this... my guess is the previous owner had a want/need to be able to activate the windows when the car was off. The DEI modules are great... Now I have one touch open/close on both windows and my sunroof. as well as the ability to open/close them with my aftermarket alarm fob.

Nick

vincent911

They do... if the door is opened
(true on european models)

MDamen

I'll have to try that. I never opened or closed the windows with the door open.

My BMW, and my VW also, had the ability to open or close the windows using the key in the door. That would necessitate battery power to the windows. I don't think there is any such feature on the 993.

geolab

In ROW thus I don't know for US models, without keys in ignition, if you open the inside door handle, even if the door is jammed, you can open the windows and the sunroof with the handle pulled.