amomin2321

So for some reason my car battery dies every two days. If I drive the car everyday then it's fine but if I skip a day then the battery is weak and I have to jump the battery. I started removing fuses to see what could be an issue. I removed the radio, ac unit, and cigarette lighter fuse but it still died. Do you guys have any recommendations on what I should look for next? I appreciate your help.

C24FUN

Any trouble with battery discharge really needs to start with good information on what the level of current drain is and then narrowing it down to the root cause. The best way to do this is with an inexpensive multi-meter. Almost anything you can find on Amazon for more than 25 bucks will work fine for this type of investigation.

First step is to disconnect the negative terminal from the battery. Be aware, an accidental short circuit across the + and - battery terminals is very dangerous so use care. Now, with ignition off and no known power drains (lights off, doors closed etc.) you can measure the current flow between the negative pole of the battery and the ground lead that you just disconnected. This requires understanding how to use the multi-meter to read current, so either read the manual carefully or ask someone if you aren't 100% sure. If it's anything much more than about 50 milliamps you have a leak somewhere. If it's in the 40 - 60 mA range, you probably have a bad battery.

If it's not the battery, next step would be to open up the fuse box in the frunk and while still monitoring the current flow at the negative battery terminal, removing fuses and/or relays one at a time and see if the current flow changes significantly in any circuit. when you remove a particular fuse/relay. You have to familiarize yourself with the various systems powered by each fuse/relay to figure out what might be the problem downstream.

That is how I would get started. How you proceed sort of depends on what you find.

Cheers (and Happy New Year)!

Jim G.

amomin2321

Thank you. That's great advice. I will attempt this soon and let you know what I find.

ChrisI

Check your door switches. Do your windows still work without the key in your ignition? If so your door switch may be shorting and causing a current draw. The rubber boots on the door switch tends to tear and allows mositure in, fouling the switch.

amomin2321

Switches do work even after removing the key from the ignition but they stop working after opening the door. Is that normal? I have replaced one switch when I had the engine rebuilt. Thanks for the input.

ToreB

Here's how to properly test the battery draw in the 964:
https://www.bergvillfx.com/categorie...nt-measurement
Cheers,
Tore

Sirenty

Yes, that is normal. At least, on the later cars. Might be all years.

MRogers

Some more ideas in this one

amomin2321

So I finally got around to testing the methods you guys suggested. The good news is that I found the problem and it isn't as simple as the door switches. It was fuse 16 that was drawing excessive power, which is ABS. I'm not mechanically inclined so don't know what my next steps will be. I have had the rotors/pads and alternator replaced when they did the engine rebuild. Also the brakes do feel stiff as if it is not power assisted. I didn't drive this car before the rebuild so I don't have anything to compare the brake feel to. I wonder if my ABS controller is faulty or the pump. Please let me know your thoughts on this. I appreciate all the help you guys provide in this community

ToreB

A known issue is severe corrosion on the ABS control unit main connector. This unit is mounted in the front right frunk. Unlock the safety lock and undo the connector to inspect. Any corrosion issues will probably involve more than the connector, also internally.
They mounted the unit upside down in the 993 to avoid this problem, leaking frunk rubber gaskets are not uncommon.
Cheers,
Tore

amomin2321

Thanks Tore. Also amazing work on repairing my CCU. It works great. Would anyone have any pictures to guide me on where to look?

ToreB

Thanks, it was my pleasure.
If you google "porsche 964 ABS control unit position" you'll see.
T