isakpede

Hi.

I have a power drain problem on my 1994 928 GTS. I have measured (and eliminated) the drainage to be at connection K24 in the Central Electrical panel.

The consumption is 120 mA when K24 is connected and just 20 mA when it is disconnected (with the doors locked and alarm activted).

I have studied the electrical drawings but cannot figure out what K24 is connected to. The only thing I know is that I hear clicking under the centre console or under the drivers seat when it is energized.

Anyone who have had similar experience or can interpret electrical drawings better than me?



Regards

isakpede

Randy V

Alan will be along shortly to assist.

In the meantime, how about an introduction and pics of your car?

Rob Edwards

Per the 1994 wiring diagrams, K24 is the output of Fuse 18 (fed by the X-bus) and (I think) has to do with the sunroof motor. Is there a problem with the sunroof operation?

Bilal928S4

If it is for the sunroof, try disconnecting the switch on the console and see if the draw goes away.

worf928

Don't forget that after '90 the sunroof circuit runs through the box under the driver's seat.

One possibility is that that window/sunroof controller is going south.

SteveG

I may be jumping ahead here with a new user, but from the question, you should read the New Visitor thread and you should probably get a battery maintainer as well. It's very hard to get the drain down to 30 mA, so at best you still have a drain. Not knowing anything else about your car or its habits, mind you. Welcome.

Alan

Your power window controller (under drivers seat) is staying active after ignition off and doors open (when it should normally turn off). You should find the windows & sunroof are always active - they should not be.

Do your interior lights work normally in door switched mode? If not that is the cause. If the doors are not detected to have opened the window controller will never shut off.

Windows/sunroof controller turns on (windows active) with ignition-on and off (windows in-active) only with ignition-off AND door-open

It is then also likely that your hatch release pull switch doesn't work either - same reason.

Try both doors - one may work and the other not...

Alan

isakpede

Hello guys and thanks for all the prompt replies.

I detached the windows controller unit today and found that when I disconnected pin # 31, which is ground, the power consumption fell to 29 mA.

This means that it is always a 100 mA consumption through this box.

All doors and lights is functioning well, and after ca 10 sec. the Power consumption reduces from 500 mA to 129 mA. If I pull pin 31 on the windows controller it drops further down to 29 mA, with the doors closed and alarm activated.

Does this mean I have to change out the controller unit?


Sorry, no new pics, as we had 50 cm of snow in southern part of Norway today.


regards.

isakpede

Mrmerlin

what Alan is giving you is a push to clean the grounding points of the door pins,
and the hatch, deoxit is your friend

Randy V

Fail.

We don't need NEW pics.

Alan

Sounds like your controller is toast - you can try opening it up and checking the relay function - sounds like the main power relay is stuck on - there are 6 relays in there - they all look the same - test them all (move the sprung contacts) - check for clearance. You have nothing to lose.

Alan

worf928

Based on the above its not clear what the static draw should be with doors locked, alarm active, (and a timeout)?

Alan

29mA is an acceptable number. In general I'd say <30mA is quite OK, above 50mA suggest a real problem. Stock should be about 15-20mA (mine is currently about 18mA).

However it does depend on after market equipment installed - especially head units and amplifiers since they have constant battery power and a turn on mechanism, so parts of them are always on. Other equipment that has constant power as well as ignition/accessory or a turn on signal, (so say add-on alarms, alternate engine management, keyless entry, alternate fan controllers, antenna amps, cell phone interfaces etc etc.) also all contribute to this.

You are also right there is a timeout after running for the fan controller to turn off. So do current measurements cold - else wait ~30-40 mins.

The alarm active does impact the number too, so less with alarm off. There is a bigger effect for this in the models with LED lock posts - but its a pulsing current, difficult to measure - but the higher average current does impact battery drain.

Alan

worf928

I wasn't specific enough: it's not clear from your description what the window/sunroof controller should do after the doors are closed and locked after a few minutes. I assume that after a couple of minutes it should quiesce and have zero standby draw. Yes?

As for car-wide standby current draw, yes, I agree <30-50mA is what I would expect if everything is perfect with totally-OE equipment. At least for pre-89s. I've never had to hunt all the mAs on an '89 or newer.

For the older cars - and I would presume the newer ones too - the alarm circuit can be worst offender. As long as the alarm controller thinks any of the hatch/doors/hood etc are open it won't quiesce.

Alan

Dave,
Its simpler - as soon as the key is out and a door open the controller should immediately drop to <1mA.

The controller itself has a small power control circuit that is always active - all the rest is turned on/off

Alan