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oprj45 · Joined: 19 Jul 2005 Posts: 23 Location: San Francisco, CA

I'm upgrading the Blaupunk radio and hit a snag.. i can't get power to the radio anymore.. i think it has to do with this mysterious White Plug?

bascially my Blaupunk worked fine.. i.e. powered up, ant. raised/lowered.. fm/am reception normal. then i pulled it out so i could upgrade.. looked at the wiring and pluged it all back in just to check things and then the radio wouldn't power up.. figured maybe i killed it with some good o' brute force

got the new radio (Crutchfield rocks!) .. wiring was pretty straight forward (used Connectors).. plugged in the harness and powered on the car.. still no power to the radio! i'm pretty puzzeled.. the only thing i can think of is there is an extra white plug connected to the red power wire that doesn't seem to have a "home".. there's no connection for it on the Blaupunk.. maybe this is a series circuit that got unplugged and thus everything on the line is dead? but where does it go? i've attached photos below.. it's the only white plug .. everything else in the area has power.. the lights for the clock/gauge/cig lighter/heater/fan/etc..

i'm going to get a voltage meter tomorrow and see if i've got current..

any ideas? anybody know what that white plug is for? and why it has two lines while the radio uses a single [red] wire?

thanks so much!!

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Porsche 924 - 1982 - Northern Cali

leadfoot · Posted: Sun Nov 20, 2005 5:13 pm Post subject:

To start with, unplug the harness and test that you have the right power going to the right connection... I.E
red 12V constant
yellow 12V through ignition - and 12V being supplied when ignition is in accessories position
black ground
If these are not getting the right power then check the fuses are not blown, (radio fuse at the fuse box and the inline fuse on the 12V direct connection to the battery)

If these all check out good....
check the fuse on the back of the new radio... is it blown...

If all these check out you should have power or your radio is defective... as this is all it takes to power one up....
the aerial connection (powered line) will only help with tuning to a station, it is not paramount to the powering of the unit.

As for that white connector ?? I don't know, I went through my entire loom and pulled out all that stuff along time ago, there are a heap of extra cables not used in the loom. It vaguely reminds me of a connection used for the air con system, but it could be for cruise control or some other accessory not present in your model.
Leadfoot
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Smoothie · Posted: Mon Nov 21, 2005 2:21 am Post subject:

Pg 296 of the Haynes manual shows a 2 terminal connector labelled "T2k" at the far left side that should have a small 1.0 metric gauge red/blue wire and a larger 2.5 gauge brown wire. If those are the colors of the wires in your mystery white connector, then it is connector "T2k". -Then the brown is ground and the red/blue goes to pin 87 of the radio relay and should show 12V+ when the key is inserted. You should find the radio relay clipped to the left side of the hvac unit.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Voltmeters are usually used for checking for the presence and level of VOLTAGE, not AMPS.

With the greater and greater demands being made on the electrical system on the later 924s, the total current capacity of the ignition switch was becoming a concern to Porsche ( look at the number of failed electrical portions of the ignition switch). Porsche added the radio relay to the electrical circuity of the car to decrease the direct electrical load on the ignition switch when the ignition is switched on.

Unfortunately, the radio relay is not installed in 95% of the cars that came with the radio relay prewired, because the Dealer and Aftermarket Radio Installers are HACKERS, who were/are not aware that the car came from Porsche/Audi prewired for the radio, with the radio relay socket. Because of this the odds are that you will find the radio relay socket secured in the wiring harness up under the steering column.

My guess is that you may not have an adequate 12+ supply or proper ground wire for the sound system. Since the radio installer may have tapped into the electrical system virtually anywhere under the dashboard, he/she/they may have connect the power and gound to places in the electrical system that are inadequate for supplying the amount of power that your new sound system requires.

You may have a bad or defective connection, did the previous installation use wire nuts or just have the wires twisted together? You didn't solder the wires together either.

Or, you may have a blown fuse. Did you find a fuse on the back of the old radio? When you removed the old radio, did you find the inline fuse holder? The wiring harness supplied with radios always includes a fuse holder on the 12+ wire. Maybe the fuse holder is higher up on the power wire you reused from the original installation, and it has a blown fuse.

There are available open switched and unswitched terminals on the back of the fuse panel, and a master/major grounding point up behind the fuse panel. There is no reason that the power and ground could not have been connected safely and securely to adequate/properly locations.

The radio relay does not/did not come with car when manufactured. The competent radio installed was supposed to supply and install the radio relay as part of the sound system installation.

So, most probably, you will not find the radio relay clipped to the left side (car's left side) of the heater box for these reasons.

Personally, I would recommend going back and removing the wiring added by the first radio installation, and connecting the wiring for your new sound system directly to the wiring provided by Porsche in the car for the radio installation. Use the radio relay wiring, and install the radio relay. Connect the new wiring to the car's wiring by soldering, and not wire nuts or twisting the wires together (and covering with tape). That is how you make a good solid change (or addition) to your car's sound sytem with causing problems (fires, intermittent function, or poor quality sound reproduction).

If you are not experienced in doing the job right, get someone who is to help you. There is no shame in asking for help. Just make sure that you listen, and learn.

oprj45 · Joined: 19 Jul 2005 Posts: 23 Location: San Francisco, CA

ok well i disconnected everything and got a multi-meter.. but i'm not getting a signal on anything, key turned/etc.. so it sounds like a blown fuse now.. i can find the fuse box, but i don't know which one it is and i don't want to just start pulling things i don't know about. any idea which fuse is for the radio? 1-15?

it really sounds like that white plug is for the radio relay, but i still can't find where it goes.. got on my back under the wheel, pulled out the gauges.. looked everywhere, still can't find it's home.. so most likely not being used..

one more than.. i just stuck the ends of the meter into the plug and the VU maxed out.. then i tried it again and now i get no signal..

any ideas? thanks so much!!

oh btw.. yes, going to solder for the complete install.. just using connectors to make sure everything's cool.

_________________
Porsche 924 - 1982 - Northern Cali

Ozzie · Posted: Mon Nov 21, 2005 11:08 am Post subject:

Fuse 7 IIRC
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

What kind of voltmeter did you buy, and what scale have you been trying it on?

If you select the wrong scale or the wrong function, you might get the wrong reading, or short the meter out.

Did you buy one of the cheap voltmeter that has a bunch of different holes to plug the test leads into instead of a function selector?

If you had the meter set to read ohm (resistance), and you connected it to a power source, you might get a reading (incorrect), before the meter itself is destroyed. But then, something inside of the meter would let go (hopefully a fuse, but don't bet on it). then the next time you try the use the meter, you might not get any reading on it.

If the radio installed did not use the radio relay, there is no telling which fuse the radio hot lead that he installed is connected. Certainly it is not going to be on Fuse 7 where the other List Member wrote that it will be.

If the radio relay is not installed, you will not get any 12+ on the large red lead in the white connector you have asked questions about. The radio relay switches 12V+ to the radio, only when the ignition is on.

You can try following the large red wire from the white plug back into the wiring harness to find the radio relay.

You can also try following the read wire that you connected the new radio's wirng to up instide the dash to find out where the previous radio installer conected the 12V+ power supply to.

oprj45 · Joined: 19 Jul 2005 Posts: 23 Location: San Francisco, CA

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Ozzie · Posted: Mon Nov 21, 2005 1:38 pm Post subject:

Nothing.
A voltmeter (ac or dc setting) has a built in resistance to prevent current flow and burning out. The volt drop across the resistance is what is measured.
If switched to amps or ohms that resistance is bypassed and phht! , meltdown.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

No, NOT DC AMPS.

AMPS is the speed (How Fast) that the power is traveling.

VOLTS is the volume (How Much) that is coming through.

Voltage is measured across the component that you want to check. You are supposed to connect a voltmeter with the test leads on the positive and negative leads that are attached to the component you are driving to measure.

Amperage is measured inline, meaning that the power is actually traveling through the component and through the meter. Amperage is measured going through the component AND the meter, The meter leads are attatched between the lead and the terminal/connection on one end of the component. Example: one lead is attached to the wire that is supposed to be the 12+ source from the car. The other meter lead is attached to the terminal where the 12+ source wire is normally attached to the component that you are measuring the AMPERAGE through.

What a meter will do when you connect it incorrectly varied from meter to meter, and depend on how you incorrectly connected the meter. Some mistakes will blow a fuse, and some mistakes will damage components inside of the meter. The worst mistake you could probably make would be to connect the test leads from the meter to something with the something has power running through it, and have the meter set for ohms.

If you use a meter, eventually you will make a mistake and damage it. To help ensure the longest life for your meter, it is very important to always disconnect the test leads before changing settings, and double check the meter settings before connecting the test leads to take a measurement.

DC Volts is what you want the meter set to. There is a difference in the way that the meter is wired.

If you set the meter to read AC Volts, when you are trying to read DC Volts, you will get an incorrect measurement.

Paul · Posted: Tue Nov 22, 2005 10:53 am Post subject:

The way I think about amps and volts.....

Amps: amount of electrons passing a point
Volts: pressure of electrons flowing
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Smoothie · Posted: Tue Nov 22, 2005 11:04 am Post subject:

Same here. Think of amps as a volume and volts as pressure.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

oprj45 · Joined: 19 Jul 2005 Posts: 23 Location: San Francisco, CA

ok well the meter is fine.. just blew the fuse. so using 15 DC V, i was able to get 12V on the batery and 12V on the clock. i don't however get any readings off the [radio] red (power) and black (grnd), or when i plug the probes directly into the white plug. i did get a reading off the white plug yesterday because that's what blew the meter.

so now i think it's safe to say that
a. the radio relay is installed
b. i blew the radio relay fuse

but i still can't find where the plug actually goes.. that's the most frustrating.

re: the fuses.. (sorry still new to this car

) they don't look like anything i've ever seen before.. piece of plastic with a strip of copper in the middle? how do you know if it's blown?
_________________
Porsche 924 - 1982 - Northern Cali

Lizard · Posted: Tue Nov 22, 2005 12:09 pm Post subject:

the strip of copper has a blown spot in the middle, if you take out any fuses that are blown the copper will fall off either end.
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