Hi I'm a newbie, just bought my first car ever, a 1990 TP Wagon GLX, manual, carby, A/C white and it goes great! Only had my P's for one and a half months and ths car is the smoothest and quietest in our family of 3 cars, I'm stoked.

I'm trying to install a JVC head unit to replace the standard one but the wiring has me (and my dad) baffled. He asked if I could list the wires from the wiring loom's end block from inside the centre console to see if you could give us some leads.

They are (italics are from the old head units block),
Black/White--------grey (RF speaker)
Blue----------------blank
Green/White-------blank
Blue/Red-----------red (fused) (to ACC power?)
White/Red---------white (Clock fuse? Huh?)
Orange-----------blank
Red---------------green (LF speaker)
Black/Blue-------black (Earth)

We are planning to cut the block from the old stereo and join it to the JVC but the wires don't make sense.

Dads said it doesn't have any speaker negative wires. He asked "Can they be joined from the head unit to a common earth on the stereo mounting frame?"

Any help appreciated.

Welcome :)
First gens execpt for the elites have a common ground to all speakers so youll need to rewire all your speakers because if you use the factory wire your new headunit wont like it lol so nar dont join the earths on the stereo frame

But somethings not right with the colours, do you have enough room to go back further to the original wires? if you can,
Blue is Acc (normally goes to blue on new units)
Red/white is Permanent power (normally yellow on new units)
Green/white is dash lights (normally orange if new unit has it, just dims the screen)
there wont be a factory earth wire as they use the surround to ground so youll need to just find a clean screw/bolt to earth too

you can run new wires for most things, and will need to for speakers. worth noting however that if your just using a new headunit and no amp, the new headunit might draw to much power and need its own constant ran from the battery instead of using the one thats there, and if you get stuck and cant work out switched power, use a multimeter on the plug to see what one is switched

the Join for the radio should be under the handbrake
did a search and nothing came up about the radio wiring

one of the wires is live to run the clock and remember the button settings
another is only on with accessories (key)
the rest are speaker wires
you need to make up a whole new earth wire to the chassis
thats is all I remember

I got Yellow.. for constant power..
and red as ACC..

All sorted and we wired up 4 speakers, 2 existing fronts and 2 new back ones. Dad sorted out the wiring, the mistake we made he said was to try to make sens of the separate wiring harness that was in the centre console. It did not match the colours from the main harness that came out of the floor. He ran new wires to the front speakers which allowed us to have an earth connection from the HU and new wires to the back. He said to thank magna buff for the "sticky" instructions to get into the front dash. He got constant 12V and 12V ACC from the harness on the floor and worked from ther to the HU. The strange part was when I helped him refit the console and tested power, lights came on as normal but I forgot to turn the power off and removed the earth wire from the HU that I screwed into the frame on the floor and the power stayed on! It was running without an earth wire. I guess the metal outer box of the HU is earthed, nobody warned me of that! It all works and sounds good, I just have to save some money and get better front speakers. thanks again evryone.

The head unit will stay on without a proper earth but you will find as soon as you give it volume there will be issues. So you do need an earth connection for it to function properly

lol The headunit is earthed as soon as you plug the aerial in, it has an earthing shield around the signal cable that is connected at both ends, to the bodywork and to ther HU case. Still a good idea to provide a separate earth though.

lol The headunit is earthed as soon as you plug the aerial in, it has an earthing shield around the signal cable that is connected at both ends, to the bodywork and to ther HU case. Still a good idea to provide a separate earth though.

I am having trouble with the aerial connection and it wasn't connected. But I did screw the new earth back on with one of the frame screws.