danfil

I know there are a lot of threads concerning battery drain on our audi's, I have a simple question ( I hope ) regarding where to start finding my parasitic drain.

As my '94 Cabriolet has had PO doing different things with the electrics I am concerned where to start.

I have a multimeter that needs replacing, gives wrong readings etc. slightly faulty so I borrowed a test light and hooked it up to the negative terminal of the battery then the other end to the cars negative terminal with all doors closed, drivers side unlocked when battery was disconnected, keys in my pocket.

The test light gives a dull glow as pictured when all the positive terminal connections are connected. I know the added in to the positve terminal makes no effect on the test light glow as have done the same layman test by disconnecting it.

But disconnecting the secondary to main clamping connector to the terminal shows the test light no continuity .

So my question is as this secondary connector goes into the wiring harness of the main clamping terminal what is its purpose? alternator, fuse box what..

This is an O.E. connector and secondary to the clamp it must go to a important sub system, starter, alternator (I know I mentioned fuse box that's what the main clamping wire will go to I am sure). . (disregard the solid red wire it was added by PO and still a mystery)



I have previously left all connectors on the positive and removed fuses and relays sequentially while observing the test light but cannot identify the parasitic drain..

While disconnecting the battery after driving the car for sustainability it would be good to find out where the problem lies..

Rusty Spokes

Some parasitic drain is normal..clock, radio memory and the engine management control computer all draw 12v with the key off.

A multi-meter that will display amps will be very handy..you need to know exactly how much current..in amps..is being drawn..your test lamp won't tell you much..it is illuminating because there is some current draw..is it normal? Maybe or maybe not.

If you get a multi-meter and check the amps draw from the battery ground to chassis (like you did with your test light) you should not have much more than a few mille-amps with the car shut down.

If it is much more..pull fuses till to amps drop..there is the problem.

Prior to starting work be sure all the dome lights..glove box lights..trunk lights..are OFF when the keys are removed..also the ignition switch has been a problem on our cars too..that could be leaking voltage too.

danfil

Following this wire from the battery terminal, I find it winds its way from the terminal close to abs unit then to the firewall and through it.

This is on the vehicles front left side, the drivers side in the U.S.A. but not on this Australian build vehicle.

Just speculating could it be going to the convertible top motor and mechanisms?
Also could go to the ecu?

Just speculating what would require an O.E. positive connection to the terminal other than the main connector for the battery.

I am not ready yet going to start stripping down the car and or wiring harness..

Rusty Spokes

The engine ECU has 12v power all the time to hold memory as does the radio, the clock, the anti-theft alarm, door locks control unit and maybe the seat memory and others.

Rather than chasing the draw of 12v with a test lamp through the firewall..which may be powering a normal accessory or computer function ..just get a decent VOM..you only need to measure less than an amp.

Amazon ships to the Pacific rim very cheaply.

danfil

Hey rusty not sure if this is completely accurate, and I am not sure if the multimeter's leads are the correct way around when contacting the battery and the negative connector..

Is this normal?

I have done some electrical tinkering and adjustments since the overnight drain of the battery so that it did not have enough to start the car in the morning..

I just out of habit and fear of not being able to start in the morning have since always disconnected one terminal off the battery.

Rusty Spokes

Looks like you hooked it up just fine..negative battery post to ground..and .2 amps draw on the system. Now just pull fuses..one at a time and see if the draw drops..then you know what circuit is pulling. Be sure your doors are closed and the dome/trunk/glovebox lights are off. The dome lights probably have a gradual dim light feature when the doors are closed..be sure the light is off.

.2 amps sounds a little high 200 milli amps.That should not kill a battery overnignt it is only 2.4 watts of power draw on a good 12v battery you should be able to go a week or two..but pull fuses and see what will drop the draw.

Your battery may just not be in good shape..what voltage will it show after a day disconnected?

tenspeed

I found this video pretty much covers how to check for parasitic draws. It starts with a battery check.

danfil

The battery voltage overnight after being disconnected is close to 12.5 volts.

This seems fine enough, with adequate amps also (unmeasured) to crank over the engine in the morning or whenever I need to drive.( after reconnecting battery of course)

I am considering testing the battery at an auto store Rusty but suspect its not a problem, since it always starts the car even over say five or six days of disconnection.

tenspeed the video was very good, I watched it very attentively, followed the instructions of pulling all the fuses in the fuse box under the bonnet, with no Amps drop.
I think there is a another fuse box in the cabin somewhere.

And while using the 'wonky' multimeter after disconnecting it the numbers did not change until I had shaken the multimeter = faulty test equipment...

Looking now for a work around these issues..

Lago Blue

Hi Dan,

The reason I am directing you towards this particular thread (see below) is because:
a.) Despite that you may have found plenty of threads on the subject, you haven't said that you have checked any of the most usual suspects off your list;
b.) the subject thread contains most of those suspects; and
c.) I think you're on the right track and that what you have done so far is trying to tell you that your drain is something that is -not- fused.

Find thread by "jkid" from 12-11-2003. titled "battery drain???"l

Sorry, as usual, this forum alone in the universe gives me t functionality. rouble.

In particular, see the two posts at the end by "90QuattroCoupe" and "DINA".

Consider also that both ignition switch replacement and the trunk-hinge wiring mod ar. e "must do" items. if. if you have not done them already.

BTW, if I understand you correctly, the 2ndry OEM positive wire you are trying to identify will feed the starter motor via the starter solenoid. That it indicates "no continuity" with the ignition switch -not- in the start position is a good thing, but perhaps you already get that, correct?


Hth

Audiworld, please fix your forum!

danfil

I have just ordered a new ignition starter switch ex-usa.

Will post after arrival, install, testing..


Dan. F.