Bow_Tied

iTrader: (1)

Hi All,

My car will, sometimes but not always, drain the battery dead in a few hours? days? of non use. I have not owned the car long enough to say how long it takes as it doesn't do so consistently. It may be a red herring, but the PO revealed the issue before I purchased; he believed it was the original goodwrench alarm system. His solution was to put a battery disconnect switch and disconnect after every drive.

My first couple of attempts didn't find the power draw as I was focusing on the alarm. Tonight I discovered pulling the lid fuse made a difference. What I found interesting was the power draw pattern:
Connect the battery in series with the DMM and watch the DMM on 20A setting:
5-6A draw for 20 seconds.
Then 0A draw for 1-2 seconds
Then 5-6A draw for 1-2 seconds
repeat the 1-2 seconds on/off.
The above was repeatable. Pulling the 'LID' fuse reduced draw to 0.1 mA or less.

The power hatch works great. Struts are excellent and pull the hatch up quickly (not sure if replaced since new). I have had a couple of times where the pull down mechanism didn't raise up and I had to fiddle with it to get it to come up and then fine. Motor always pulls down at that point.
My hearing is poor so if it was humming I might not hear it.

I have read numerous posts and realize the hatch pull downs are problematic. My car has 33k miles if that matters, but I am guessing this is more of an issue of age than miles.

Even though the motor works fine is it likely the issue? Could be an adjustment that occasionally let's it think it is not all the way down? Intermittently bad relay?

I am ok with replacing parts but don't want to replace things randomly, I would like troubleshoot this further. Thanks for any suggestions.

OrangeBird

iTrader: (1)

Ron I won't try to play expert here , but if I was to guess the first thing I'd check would be the switch that indicates the closed position . Like you were thinking , my thought is that if the switch was faulty (or misadjusted) it would keep the motor trying to close the already closed hatch . These motors usually have a thermal cutout in them to protect from fire if just such a thing were to happen , the motor receiving power when it shouldn't , and the thermal switch (inside the motor itself) cycling would be a great reason for what you were seeing with the "sometimes on/sometimes off" current draw .

Bow_Tied

iTrader: (1)

Thanks for the reply, OrangeBird (sorry, I don't know your name).

I need to get more familiar with the bits of the assembly and the functionality. I lot will become more apparent when I get time to take the inner panels apart and get in there to see. I can't do it in my garage easily so I will wait for a nice sunny Saturday, if we ever get one.

Are there any other parts of the car that require the LID fuse to function besides the pull down?

Tibo

iTrader: (15)

The above schematic is for a 1992 model year but is probably the same for your year. You can find more schematics at www.austinthirdgen.org under the wiring diagram section.
Measure the parasitic draw with the lid/hatch fully open and again, Keep the lid open and pull the light or connector for the hatch and check the reading again. Put everything back together and close it and pull the connector for the hatch and take a reading. That should help you narrow the possibilities.

Bow_Tied

iTrader: (1)

Awesome, thanks so much!