gomez123

I have a 1984 928s that I just purchased and I'm going through the car finding issues and making plans for repairs. One thing is a parasitic draw that is pulling .35 amps. Before I start tearing into this do you guy's have any quick suggestions from the board that may help. I have all the work shop schematics but thought maybe there's something common to look at first.Since I'm new to these cars I could use some guidance on common problems.

danglerb

Did you measure the draw with all doors etc closed after about 20 min or so?

You might want to get a door pin closing tool, they are called sanity something, buzzer maybe.

Speedtoys

Mine was hatch alarm switch.

SteveG

Is there anything aftermarket on this car?

Lots of reports about door lights (the red warning light) and dome lights, esp. the one center front of headliner somehow grounds against frame. Doesn't seem those lights would even cumulatively add up to .35, but I would start there.

gomez123

Thank's for the reply's everyone. I found the r/s door switch is broken off so the two door lights are on. That brings the draw down to .1 I'm okay with that.

dr bob

100 milliamps is still a lot of parasitic drain. Later cars with engine brain memory and such are less than 30 milliamps. Yours should be zero except for radio memory and clock at under 15 milliamps. 100 milliamps will draw down the battery at least 25% in less than a week, to the point where battery and alternator life are compromised. Keep searching for the leaks. Or install a disconnect and use it whenever the car isn't driven for more than a day.

Tomkat80222

So Bob, you're saying that even with a battery minder this will still shorten the battery and alternator life?

StratfordShark

gomez123

Still looking for the remainder of the draw. I just removed both door panels to replace check straps. Will continue the search tomorrow. So I need to find a 70 milliamp draw to bring it down to a acceptable level correct? Any ideas? I'll start buy pulling fuses that are live with the key off and work from there. It has a alarm system I think that will be the first approach I'll either disconnect the ecu or pull the fuse. I'll report back.
Thanks guy's

The Forgotten On

Feel the tops of your relays for any that are warm after hours of sitting is what I did to find any parasitic draw in my 81. A new 53 relay fixed that for $10.

dr bob

my "smart" maintainer cycles based on terminal voltage. The more paraitic load there is, the more frequently it cycles. My first preferencee is a disconnect; second option a smart maintainer. The total number and magnitude of the cycles determine the degradation of the battery. If you want it to last a long time and start on demand, it's best to find the leaks and drains and fix them.

My S4 leaks about 25 mA, thanks to keeping the clock in the radio current, and maintaining the memory in the LH and EZK. Each of those leaks is easy to identify by opening the connectors. Note that the '84 in question doesn't have any of the adaptive tuning and memory requirements that the S4+ have. Parasitic loads in the OP's '84 car are limited to radio memory and clock, and other accessory loads from aftermarket pieces and faulty factory equipment.

NoVector

+1 I used an IR temp sensor based on Stan's (MrMerlin) post in a thread. I had 3 relays that were significantly warmer than the others.

docmirror

Couple things. First, for your car, you should reduce about 85mA down to 15, not 70mA to get down to 30 for a 1984. However, the alarm will draw some as well, so the answer is not fixed in stone.

The alarm on these cars is notorious for being a current hog. I would take all fuses and all relays out, disconnect the harness at the ECU, and pull the connector for radio and clock. These are the known current draws. Then the only current draw you have should be the alarm. Test with the windows down, doors, hood, hatch closed, key off(of course) and wait 15 min after closing doors to take your reading. If you still have ~100mA then you've got something aftermarket, or the alarm is pulling the amps. Fix it from there, and get down to zero if possible. Then, once you have found your minima, you can go back and insert fuses, relays and connectors one at a time to see where things go wrong. Quite often it's not one single load, but several different things that start up when fuses or relays are inserted. Time consuming, but worth it.

gomez123

Thanks everyone I found the draw It's the power antenna! Thanks for all your suggestions and help.

GT6ixer

So what is the fix there?