924Board.org

[xanderdeg]

I have a '78 924 that I bought in the summer, it has never had any major problems up until now. I recently installed a stereo because there wasn't one when I bought it, I wired it with a friend a few weeks ago and since then I've had two incidents involving a dead (or severely drained) battery when I go to start it. This doesn't happen all the time, but it's happened twice now. We wired the stereo to the cigarette lighter for the constant current, and to the ignition for the switched current. I'm not sure if this is what is causing the problem. I left my car yesterday at 3pm and when I came back to it this morning at 815 the battery was dead and I couldn't start it. I didn't leave anything on overnight and the faceplate was off of the stereo head unit. Can anybody help with this problem? Thanks

[xanderdeg]

I haven't had time to look at anything yet so I'd just like to know where to start or what to expect. It's been my reliable daily for almost 5 months now so obviously I'd like that to continue seeing that I need it to get around.

[rat]

Check youve not switched the main and ignition supplies to the stereo. Most of the looms that come with stereos I've had include an easy to swap pair of wires for these two feeds.

[xanderdeg]

I'll look into that, what do I look for to determine if that's the case? My friend did all the wiring and he had all the stereo tools. He lives pretty far away so he won't be able to come out until Monday.

[ideola]

Also, test the relay to make sure it is closing correctly. If you re-used the factory relay, it's possible it is bad and not closing when you depower the car, allowing the battery to drain.
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erstwhile owner of just about every 924 variant ever made

[xanderdeg]

I will check all of that, thanks! My confusion is why this has only happened twice in a week and a half. Wouldn't this type of problem be constant, and not Intermittent? I've started my car successfully in the morning or after long sits many times since I installed the stereo... That's what baffles me..

[ideola]

No, the relay issue can most definitely be intermittent; I.e. One time it may function correctly, and the next time it doesn't quite close all the way. Moisture and humidity can exacerbate this problem.
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erstwhile owner of just about every 924 variant ever made

[xanderdeg]

Well moisture is definitely a problem up here in vancouver ill check it out, thanks again, this forum is excellent!

[SlayerSST]

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[ideola]

If the relay is bad and sticks, it will drain the battery whether anything is connected or not. These relays are mechanical, and they do fail. I had this exact problem on my 928 (although not on the radio circuit). Bugger to track down.

Speaking of which, don't assume it's the radio circuit. There is always the possibility that it's another circuit where the relay has coincidentally begun to fail.
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erstwhile owner of just about every 924 variant ever made

[xanderdeg]

[xanderdeg]

Where is said relay? On the fuse box or on the ignition lock?

[ideola]

The stock radio relay is not in the fuse block; it has a clip that is used to afix it to the heater box assembly, usually accessible in the driver footwell.
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erstwhile owner of just about every 924 variant ever made

[agfisher]

How about watching the current draw at the battery when the car is completely off. Should show you if there is a drain somewhere.
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1977 924 N/A Martini Edition

[xanderdeg]

As far as I can tell we're not tapped into or attached at any relay near the fuse box, I believe we started a new current flowing from the ignition lock. And yeah I plan to check for draw on anything and everything this weekend