[flash]

my turn to ask for help

so, i'm in there digging around in the wiring while installing the new stereo, and once again i came upon the skinny brown wire with a blue stripe - this car has always had an aftermarket stereo in it since i got it, and subsequent systems worked fine, with no ill effect from that wire not going anywhere, so i never bothered to figure out what it was for

well, this time i just really wanted to know, because i am going to button it up once and for all this time

it has about .4 volts on it - that tells me it's a sensor wire - a look at the wiring diagram confirmed it - it was the radio alarm contact wire - this goes to ground after going through the radio case

my theory is this: the system is constantly "seeking" a connection to the radio, and sees this sort of like an open contact switch, but for whatever reason, doesn't trip the alarm

so, here's the $64,000 question: should this be grounded to the chassis? can this be grounded to the chassis? is there something else that needs to go inline first?

also, the skinny black wire that parallels the coaxial antenna cable, terminating at the antenna amplifier goes to the little molex and into the skinny red/black wire - that then went into the molex connector and plugged into the back of the factory radio - the question is this: is this ground or power that it should be connected to? the wiring diagram is no help, and i don't have factory radio to tap to see what is at that pin - also, why the heck is that wire black?

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[flash]

local stereo shop confirms theory - brown/blue wire goes to ground - try at your own risk

still working on the antenna booster wire

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[Darryl]

My guess would be the skinny wire running with the antennae lead would be for remote power on or some other kind of status that needs to go back and forth from head unit to antennae amp. I'll take a look at the schematic tomorrow at the shop.

Congrats on the skinnny alarm wire...I thought it was gray with a blue stripe, but anyway...I know for a fact mine is slapping in the breeze and was that way when I tore out the PO aftermarket radio. Grounding that makes my battery hold a charge longer?? My car stays plugged in now, but it certainly can't hurt having one less wire flapping around.

- Darryl

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[xrad]

Wiring dgm says radio alarm wire goes to plug II, pin 9 on alarm...you could look there to match wire color....

But No color indicated on dgm for alarm wire...

Porsche wiring dgm pictograms make it look like the wire goes to ground, but I think that is the way Porsche draws connectors. Looks more like it connected to radio pin 6 for some radio models and it does not look like it goes to ground

would not make sense to run it to ground at the radio...why waste 3 feet of wire??

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[flash]

look at the wiring diagram model 93 sheet 7-2 - it is also known as 97-45 page 2, or page 668 if you use preview - it is the center page of the central locks, alarm system pages - it clearly shows the brown/blu going to the radio case and then to ground - it is a wire intended to determine if the radio is being stolen - it sends a small voltage in a "is anybody there" fashion - that drains the battery over time if it isn't grounded

i think i have finally nailed down the battery drain issue that many of us experience - i'm willing to bet that nobody with a stock radio has a problem, and that it is those of us with aftermarket stereos who have not addressed that wire

as for wasting 3 ft of wire, i did not suggest that - i only said ground it to chassis - plenty of places to do that in less than 12 inches - heck, there are 5 ground wires right there that i could tap

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[jaap]

<!--quoteo(post=67073:date=Feb 15 2009, 12:58 AM:name=flash)-->QUOTE (flash @ Feb 15 2009, 12:58 AM) <{POST_SNAPBACK}><!--quotec-->also, the skinny black wire that parallels the coaxial antenna cable, terminating at the antenna amplifier goes to the little molex and into the skinny red/black wire - that then went into the molex connector and plugged into the back of the factory radio - the question is this: is this ground or power that it should be connected to? the wiring diagram is no help, and i don't have factory radio to tap to see what is at that pin - also, why the heck is that wire black?<!--QuoteEnd--><!--QuoteEEnd-->

I am not sure what you mean by molex etc, but the black wire which is parallel (fused with) the antenna cable should be connected to power for the amplifier to work. My aftermarket head unit has a dedicated output for this purpose which supplies power when the radio is on. However my car is a coupe with the amplifier in the base of the roof mounted antenna, but I assume the functionality is the same for the cab with it windshied antenna.

The alarm wire I just left unconnected (as it has been for years) but I don't have any battery drain problems.

Jaap

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[DayDreamer]

The Black wire must be connected to the switched output from the radio. The same one you use for the remote amp power switch.

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[Anchorman]

It's been a while since I've done my radio install, so I don't remember the wiring. What I can say, though, is that I don't have the stock radio, and I don't have a power drain problem.

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[blue968]

Hey Guys,

This is very funny because I had just bought a 92 cab and it has the factory radio (does not work) but anyway the guy who I had bought it from never had a conditioner charger on the car and I had asked the question do you have to charge the battery after it sits for a while and he replied no. I thought for sure he was not being honest, well after I had bought it and let it sit for over 2 weeks the car started with no problem??? I was shocked and I had thought it may be in the radio as well because thats the only diff between my 93' and 92 cab , the 93 has an aftermarket radio and can not sit for more than a week without a charger on it or it is stone cold dead. I checked all the interior lights including the glove and nothing was on.

I plan on replacing the factory deck and i will post what that wire is doing.

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[flash]

yeah - that's what i figured on the antenna booster wire - just making sure - i never had it connected before, but reception was fine - should be better now

i'll let everyone know how it goes with the brown/blue wire - i plan on finishing up over the next couple of days - it's a really involved install, so it's taking some time to get it all in there nice and clean

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[gryphon]

Pictures please, Flash. I would dearly love to wean my 968 from the trickle charger.

Tom

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[flash]

as soon as i confirm that this was it, i'll do exactly that

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[xrad]

Flash: Yep...to case and then to ground...interrupt circuit. Voltage probably drops when circuit complete to decrease drain. I am going to look for mine...

sit in the car, gound the wire, set the alarm. then break the ground and see what happens......

anybody know where the alarm transducer is...??is it under the wiper arm cover panel??

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[rustech]

Has anyone with a drain issue pulled each fuse one at a time and check for draw with an amp meter? This is usually the best way to determine which circuit the parasitic loss is occurring. I still have the factory head unit in and still have to keep the trickle plugged in. Unused voltage on a line that has no draw does not directly translate to a loss. Hope you find your drain issue.

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[flash]

this could be a case of 2 plus 2 equals a duck for sure, but it sure seems like exactly the kind of thing that would drain the battery

no, i have not yet put the meter to it to see - lol - i broke one of the leads on my meter today as i was about to do that, and need to run out and get another one tomorrow

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[Cloud9...68]

Interesting discussion. I haven't looked at the wiring to my radio, but my car has an aftermarket radio, and I can let it sit at least two weeks, and it cranks strongly and starts without any problem. What's considered "normal," I wonder? I thought all modern cars have problems with not being able to sit indefinitely, because of all the alarms, LEDs, and other gadgets on them.

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[DayDreamer]

Flash.. you do realise that you've made all the guys with aftermarket radio's paranoid.... If Guiness World Records had to check this week end, we could set a new record for most Aftermarket-Radio-Installation-Check-in-968's. [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[flash]

lol - yeah, i was afraid of that too, but that may be a good thing - it just seems odd to me that this car dies so quickly, with new parts everywhere - i have similar alarms in both of the other cars, yet they can sit for much longer - there is something somewhere draining this car - this is just the first odd thing i've found, and applying post hoc ergo propter hoc, i am testing it out - later today i'll go out and pick up another meter and find out - i'm determined now to find it

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[flash]

well, while i now have a brand spanky new meter, it did not help me in finding the drain

i pulled every fuse, one by one, and the only one that made any difference was the clock fuse - at the 10a setting, reading went from 1.2 down to .9 (as a reference, the trunk light bounced the draw to over 8)

grounding the brown/blue wire did nothing - so, while i find it odd that the alarm still works with that disconnected, and i think it should act just like an open door, and it doesn't, that does not seem to be the problem

the voltage regulator should be .1-.2 at that setting - the remaining .7-.8, though would be normal for an ECU in any other car - so, the draw does not seem to be abnormal, but the brand new battery (second one) definitely dies after a couple of weeks

this is just not adding up

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[gryphon]

Data from a previous attempt to track down the mysterious drain:

0.10 A - no key in ignition
0.13 A - key in ignition ("P" red light illuminated)
0.72 A - hood light only
0.71 A - trunk light only
0.69 A - interior light only

I give up; back to the trickle charger.

Tom

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