David0514

I have a short some place on my 77 911. I notice when I disconnect the battery and reconnect there is a one time click noise that comes from the center of the car, around the front of the windshield. Any idea what that could be? Also, attempting to find where the short was, I disconnected the positive lead to the battery and the started pulling fuses. Between each fuse pull, I would check for voltage between the battery terminal and the wire connector that goes on it. The voltage always stayed at 12v. Does this test mean anything like the short would have to come before the fuses? Any feedback appreciated. Thanks.

RANDY P

When you say short, you are probably meaing current drain, your batt is dying right? A short to ground is easy.. Which fuse is dead?

A click sound would indicate it's a relay switch activating....That is strange. There isn't much in that vicinity that should do that, except the power antenna, or dashboard blower motor. If your car is so equipped, make sure it's not running all the time, or the fan is stuck.

Using a VOM set to read voltage in series isn't going to tell you much, you need to see current draw instead of static voltage.

Quick and dirty method is to get a good quality plain old test light, and hook it in series with the NEGATIVE cable. (disconnect the neg and put your test light between the batt terminal and cable end) and watch the light. Light on means you have current. Yank fuses till the light is off. Lights off = problem circut.

good luck.

rjp

RANDY P

Also -

If you have a short and not a drain, and your fuses are burning up, check upstream past the fusebox...Which fuse is it? If this is so, you have to check the +12v connection at each item / accessory hooked to the burned fuse. Unplug the harness from each accessory and check for continuity to ground on the power lead / wires in question. If the car is pretty clean and the connections are unmolested, it's most likely a bad accessory. My experience, factory wiring usually stays put pretty well. For the wiring itself to be suspect, it USUALLY requires the meddling of a butcher of some sort.

Doubtful it's a short between the batt terminal and fuses. If there was a short there it would've burned up the car by now, and you wouldn't have anything to work on...

rjp

David0514

Thanks, it's a drain. What does the blower moter do? Is it just for the fan to the cabin or something else?
Thanks.

Murph

Another thing you might try (easier)--since it sounds like a relay of some type is engaging whenever current is present...is to take out the relays one at a time and reconnect the battery between each time. When you have isolated which relay is engaging, you'll know what circuit the drain is on and you can troublshoot from there. The prime suspects would be the switch that is supposed to activate that relay, or the relay itself. Also, check the turn-signal switch..they are prone to malfunction in that model 911, and it also activates a relay...that may be it!

Good luck...nothing mmore frustrating than electrical problems....except INTERMIRRANT electrical problems!!

Murph

RANDY P

It's just the blower motor that's controlled by the HVAC controls, (dashboard controls)

rjp

Mark Langner

I don't know about 77's but on my 73, there is a noticible click from the clock when I reconnect the battery...