86 factory radio wiring

[DGW]

I am trying to hook up a radio but the car wires are a mystery.
All the factory connectors have been cut off the factory wires. I find 3 wire bundles that I think are for the radio but I am not sure about where all the wires go.

5 wire bundle:
2 brown wires
2 red stripe/brown wires
1 red wire

I think the brown and red/brown wires are the front speaker wires. Unfortunately since they are the same I don't know which two wires pair together and which speaker they are for. I have no idea what the red wire is for, is it a hot switched wire?

2 wire bundle:
1 yellow wire
1 brown wire
I can guess the brown wire might be ground and the yellow wire is always hot. Is that the case?

2 wire bundle:
2 black wires. One of these two goes to a little red light on the dash which I think has something to do with the factory alarm. I don't know what the other wire is for. Its not connected to anything but the lose end is hanging near the radio location.

Antenna cable-this one is easy.

This car has the antenna in the windshield so there is an antenna booster involved. The wiring diagram shows a white wire from it to the factory radio. I haven't found a stray white wire yet but if I did where should it hook to my brand x radio?

The old 911's and 914's were easy compared to this.

[86 911 Targa]

Pm me for the M/Y factory manual.

Gerry

[Synchro Joe]

https://www.modifiedlife.com/porsche-radio-stereo-wiring-diagrams/

You can start here, if no luck there I can send you diagram for 1988, or Gerry offered to send you a copy of his.

[DGW]

I have made some progress here, thanks Gerry for the factory manual pages. I ended up buying the Continental radio TR7412 and the wiring harness to connect the Porsche wring harness to the radio. I have confirmed that the wire bundle with the yellow and brown wire are the switched power and the ground. The 5 wire bundle with the single red wire should be the front speakers and the single red wire should be the hot wire. my multimeter confirms this.
My problem is hooking up the radio wires this way the radio does not power up, even if I turn on the ignition. If I hook the hot and switched wires together to the car switched the radio works when I turn on the ignition. If I connect them to the car 'hot' the radio does not power up. I have got to believe that I am missing something simple here but I don't know what. Can anybody offer some help?

[brianlay]

Many newer radios expect a constant hot and a switched hot(ignition)
You may need to connect a constant hot, fused connection to the battery which the factory harness did not provide

[FrankM_]

Originally Posted by DGW

I have made some progress here, thanks Gerry for the factory manual pages. I ended up buying the Continental radio TR7412 and the wiring harness to connect the Porsche wring harness to the radio. I have confirmed that the wire bundle with the yellow and brown wire are the switched power and the ground. The 5 wire bundle with the single red wire should be the front speakers and the single red wire should be the hot wire. my multimeter confirms this.
My problem is hooking up the radio wires this way the radio does not power up, even if I turn on the ignition. If I hook the hot and switched wires together to the car switched the radio works when I turn on the ignition. If I connect them to the car 'hot' the radio does not power up. I have got to believe that I am missing something simple here but I don't know what. Can anybody offer some help?

If I read this and look at the 1986 schematic it looks right. The RED wire (0.5 mm2) is supposed to be 'bus 30' (so always hot) and the YEL wire (1 mm2) is switched power. I can only assume that the original blaupunkts used the red (fused at 2.5 A only) to power the permanent memory and the 'main' power should be the yellow wire.

However, I have a Blaupunkt RDM126 in there now (1996 I believe) and in the installation manual it states clearly that the main power (10 A required) is used from the permanent 12V connection and the 'switched' (ACC) connection is only used to cut the radio if you shut down the car. The 'original' connections should be rerouted and the undersized RED cable should not be used.

Maybe the same for your radio as most modern radios probably work like that ?

Solution :
I ran a new red cable (2 mm2) from the fuse 3/box 3 (an underused 25A fuse for headlamp washers) behind the fresh air blower and into the cabin, just next to the radio.
This is the one I connected to the 'A' ISO connector, pin 4 which is YEL as a standard color on the connector !
I used the wire coming from the contact switch on pin 7 of the 'A' ISO connector to signal the radio to come on/off when the key is turned.
I ran a new 2mm2 cable from the pin 8 on the connector to the ground point (behind the floorboard) to supply the ground wire.

FYI, the radio has a build in 10A fuse on the back.


In all it looks like this

[FrankM_]

see also : Radio Install (TR7412UB-OR Continental)

[DGW]

Thanks for the help everybody. I think I have it. I had the hot and switched wires reversed and things weren't working. Now I need to figure out where to hook up the Illumination wire, the ashtray light wire is impossible to reach on my car.

[darrin]

Originally Posted by DGW

Thanks for the help everybody. I think I have it. I had the hot and switched wires reversed and things weren't working. Now I need to figure out where to hook up the Illumination wire, the ashtray light wire is impossible to reach on my car.

I haven't done this (yet), but relatively easy to pull one of the instruments, then you could tap into the instrument light wire on the back of the gauge and then drop/fish the wire back down behind the radio

[brianlay]

Lights for the fresh air controls are closer but before tapping into the dash light circuit, do yourself a favour and fuse that circuit at the source