TheSamba.com :: View topic - Need help finding weird battery drain on GF's 87 Cabriolet

Fri Dec 16, 2011 5:30 pm

Guys-

My GF lost her job so I talked her into selling her car and buying an 80s-era VW. We found her a cabriolet. Now whenever anything goes wrong, it's my fault.

A couple of weeks ago, it needed to be jumped after she briefly went into Walgreen's. Then again when she went to drive to her mom's last night. She takes the bus to work and doesn't drive it much, but she drove it between these two instances. So I went over there with my volt meter and checked everything out.

The alternator puts 13.9 on it while idling. With everything off, there is a drain of 12 showing between the negative battery post and its ground strap. I pulled the fuses and relays one by one, and only one took it down to 10.5: the radio, etc. That is normal. No other fused electrical element took the meter to zero when off. So, one by one, I completely disconnected everything I could think of: ignition switch (all steering column connectors) starter motor, alternator, rad fan, all of the castle grounds above the fuse box, etc. Nothing took it to zero.

The weird thing is that if I turn off the car and put the meter between the negative battery post and its strap, it starts out at 8 and climbs to 12, eventually dropping back down as the charge wears off(right ?). But if between 8 and 12 I turn on the rad fan (theres a manual switch rigged up) it instantly jumps to 12 and stays there, even with the fan switch back off, until it starts to go back down.

Any ideas?

I could really use some help with this. Thanks!

Sun Dec 18, 2011 2:38 am

My frequency valve on my 87 shorted out and drained the battery a few times. I believe the circuit bypasses all fuses IIRC.

Sun Dec 18, 2011 8:22 pm

Thanks!

Any idea how I might check it? Or where it is located? Google isn't helping just yet.

Fri Dec 23, 2011 2:35 pm

Sorry for the slow reply. The frequency valve is mounted on the fuel injection metering body/air filter assembly. The relay is mounted on the fuse box. Check for water leaking in at the fuse box also. It has a nasty habit of finding it's way into the relays and reaking havoc.