I'm new as a member here, but have been visiting the forum for years to take advantage of the wealth of technical information possessed by its members. Now, I have a problem that I have not been able to diagnose, despite extensive research and review of available information, and I need the greater wisdom of the forum for some guidance. I've read through several different threads, and tried the proposed solutions, with no luck so far.

The vehicle is a 1998 986, with approximately 110K miles. I have a parasitic battery drain problem, enough to drain a brand new, fully charged Bosch battery completely dead in less than two days. A multimeter placed between the battery and the ground lead shows a steady drain of 3.47 to 3.78 amps with the key out, all systems off, the external stereo amps completely disconnected, and all of the boot, door marker, and interior lights off. I checked this draw with three separate multimeters, with consistent readings. This is a substantial draw, enough to worry me about a fire from a short.

As I said, the battery is brand new, and I have a CTEK MXS5.0 AGM-ready, battery-conditioning charger, so the battery seems to be ruled out as the problem.

The car does not have heated seats.

I have pulled each fuse in the driver's side fuse panel sequentially (three times!) with no change to the current draw.

The car does have an aftermarket stereo with two external amps (which I installed; I am experienced in car stereo installation, and don't trust other installers to tie up and protect wiring, avoid shortcuts, and keep out rattles). The head unit of the stereo is connected to the existing wiring harness with an adapter plug, and has been in the car for many years before this problem developed, and also a short in that system should have shown up when I pulled the fuse. As I said, I have completely disconnected the external amps' power leads from the battery to rule out shorts or amps which don't shut off when the car does.

I have also disconnected the wiring from the ignition switch, with no change in the draw. I do have a new ignition switch, but since pulling the plug made no difference, I have not installed it.

I have not yet pulled relays in the various relay panels.

The only other problem that I can think of could be with the alternator/voltage regulator, and a possible short there, but I'm not quite ready to access the alternator until I have no other choice, for obvious reasons.

If anyone has any suggestions about other things to check, I would be very appreciative.

Thanks,
Lewis

 

I saw a video (Ratarossa on YouTube) where he was trying to diagnose a current draw on a Ferrari 308. He put an ammeter between one of the battery terminals and the connector. With the car off, the current draw was low and he didn't damage the ammeter. He then pulled fuses one at a time until the draw dropped. My daughter's Boxster has a current drain as well, and that's the method I'm planning to use. The only thing to keep in mind is that the Boxster will 'wake up' when you open the doors, so make sure the key is out and the door is open when you connect the ammeter in line. That should keep the car asleep. If it doesn't stay asleep (i.e.: The interior lights come on.), then you'll have to wait a few minutes.

Good luck!

 

Report back when you check those relays... and don't forget the ones in the trunk.

I can imagine the frustration.

 

I'm going to check the relays this weekend, although wedging myself into the footwell is a bit claustrophic. I'm 6'4", and there isn't that much room down there!

There are three sets of relays, according to the wiring diagram, and I know about those in the driver's footwell and the rear trunk, but I don't know where the third set is.

Thanks!

 

I believe there is a set of relays in the front trunk as well. You may need to remove some of the plastic panels and fabric panels to get to it. Hopefully someone else with experience can chime in on this. I recall it being on the driver side.