Hey all.
Recently the radio in my car was stolen. It was an aftermarket one that I put in a long time ago. It worked great before it was stolen, but now I can't seem to remember how I got it all working.

I bought the cheapest head unit I could find off ebay and also bought a volvo metra harness that I soldered to the harness that came with the new radio.

here is the harness Volvo Aftermarket Radio Wire Harness Stereo Connect Wiring VL 050V | eBay

here is the radio Deal of The Day Single DIN Car Radio with FM USB Aux Memory Car Input MP3 | eBay

Okay so installed them both and everything works except for the rear two speakers. The harness I bought did not have connections for the 4 rear speaker wires. There is a second harness that looks similar to the white one but only 4 pins, I assume that would be the connections for the rears. I tried to find the connector online but no dice. I also tried to connect the wires to the 4 pin harness but i still got no sound in the rear.

now I have don a ton a research on this but I still can't figure it out. I've read something about having to bypass the amp, or how the rear speakers go through the amp. How do I get the rear speakers working?

also, ever since installing the new radio, my car battery dies after sitting for a day of no driving. Is this because the radio draws too much current or has a phantom drain? or is it because I have not hooked it all up completely?
thanks in advance

 

be nice to know what car this was for?

our 1987 240GL sedan had no back speakers OR wiring when it was new from the factory. I had to run my own speaker wires and cut holes in the parcel shelf for the 6.5" round speakers I chose to install.

the 240's that DID have rear speakers had them hooked up to a seperate amplifier/equalizer that was in the pocket down by the shifter, with the radio in the pocket up on top.

now, if this car is a 740, or 940, well, they are all different too. year is important, too.

 

oh crap my fault sorry!! it's a 1990 volvo 240dl sedan. It came with rear speakers in the doors.

 

1990 240 Wiring Diagrams TP31558/1 October 1989


rear speakers are shown wired:

pin 1 yellow-brown to yellow-grey to left rear +
pin 3 green-brown to grey to left rear -
pin 2 green-yellow to yellow-grey to right rear +
pin 4 green-grey to grey to right rear -


far as I can tell, that's on a seperate 4-pin connector that went into an amplifier module or something (drawing unclear). but I've never poked around a 1990 240 radio wiring, only our 87 240 and my 92 740 and bunches of other cars.

this drawing shows the main radio connector as...

pin 1 - green - constant power from fuse 8
pin 2 - yellow-black - switched power from fuse 1
pin 3 - red - antenna relay
pin 4 - yellow-white - left +
pin 5 - grey-yellow - right +
pin 6 - nc
pin 7 - white - left -
pin 8 - grey - right -
pin 9 - black - ground

 

okay thanks. so if I want to bypass the rear speaker amp il just have to find it and connect my radio wires to the speaker wires going in to the amp?

also, if I want to test for phantom drain, do I just hook multi meter up to the fuses one by one?

 

to check for phantom drain at a fuse, you put the meter in the special 10A DC amps mode, where you have to move the red lead into a different socket on the meter, then remove a fuse and put the two meter leads on both sides of the fuse holder, put that fuse back and move onto the next fuse. any sustained reading much over 0.02 amps is a drain (note that some circuits might have an initial inrush of current but then taper down to zero, this is OK).

there's also some stuff powered directly off the "positive terminal" and not fused, so checking all the fuses does NOT check everything.

as soon as you're done, put the meter back in a regular DC Volt mode, as an 'amp meter' is a dead short.

 

afaik, volvo always put those amplifiers down in the bottom bay just forward of the shifter, with the radio in the top bay, so that 4 pin rear speaker connector /should/ be there. In my experience, the wiring colors are NOT 100% reliable on 240's, as they made constant changes in production.

 

alright so I went out to investigate more. looks like the thieves cut some wires I hadn't seen before.
luckily my amp is right behind the glove box, easy access. well actually maybe not so lucky because that's where the thieves cut the wires. they took out the gbox and everything. they cut 4 wires coming directly from the amp. they also cut two wires leading to a small 2 pin connector. and there's a random green wire with a rounded metal tip just hanging out by the amp. not sure what to do. will try to post pictures shortly

 

there's a 2 wire connector to the factory radio that was for the dashboard dimmable light circuit, best to NOT try and connect that to an aftermarket stereo. these wires are (radio) to grey to brown to the rheostat, and (radio) to yellow to grey-white to white to fuse 15 (to headlight relay?!?).

that random green wire is probably the constant power from fuse 8, unless thats already accounted for.

btw, when I say 'wire color' to 'wire color', what I mean is the drawing shows the wire going to an unspecified connector, and the 2nd color is after that connector. the first colors I listed are the radio side. I know this is a bit confusing, but so is this drawing.

 

the 4 cut wires and random green wire. the green wire coming from the amp is connected to the power pin of the white harness. not sure if this is correct?


this is what my connectors are. two cut wires are unknown

 

I just read your recent post, the two wires that you said go to the dash dimmer make sense, my dash lights don't work. is there a good way to figure out where they both go? the colors cut are yellow which you said goes to a grey-white wire. then theres brown which goes to rheostat. where would these be? or should i start tearing out my center console

 

got a digital multimeter? strip a bit off those 4 wires, use your multimetter in OHMS mode and see if one pair of the wires has 4-8 ohms between them, and the other pair also has 4-8 ohms. those two pairs will be the two speakers. now, use a AA or AA battery, quickly touch the two wires of one pair to either side of the battery, and you should hear the speaker softly crackle, don't hold the battery on the wires, just touch, untouch quickly, a couple times. figure out which speaker it is. repeat with the other pair. if each pair has a striped and unstriped wire, the stripe is probably +

 

the rheostat dimmer near the headlight switch has two wires, one is grey to pin 58b and comes from fuse 16, this fuse is powered when the headlights are on.

the other wire at the rheostat is brown, pin 58a, and it goes all over the place, including the instrument panel lights, the various dashboard switch lights, the light in the shifter, this is the dimmable light power (voltage should vary with the rheostat position when the headlights are turned on).

 

okay so i did some of the tests.

between the two pairs of 4 wires(stripe to not stripe)
it read 1.8k ohms. also after doing this test it blew my radio fuse. i wasn't sure that these were speaker wires so i was reluctant to do the battery test.

fuse 8 i believe. the one listed on my panel as radio and locking system etc.
it read .10 consistently. that means drain right?
my rear left door does not respond to the electronic locking system, hasn't for some time. is this mechanical or could it be my electronic short? or is it just the crap radio?

 

yeah, if you don't see 4 to 8 ohms, or something pretty close to that, they aren't speakers. maybe those are the outputs from that amplifier in your picture?

 

okay so i went back and did the fuse test with the radio unplugged. it was barely .01 without the stereo in.

alright so do i even need the amp? is it ok just leaving those wires cut and just putting a different stereo in?

 

I've disconnected and bypassed any factory amps on every 80s/90s vintage car I've owned. modern decks with "50W x 4" (thats 50 watts 'music power', which is about 17 or 20 watts RMS, still plenty) integral amplifiers work just fine unless you're going for 'competition' boombox audio, and then you'll have a few kilowatts of amps packed into every nook and cranny you can fit them. (insanity, if you ask me).

 

okay so I'm going to leave it disconnected but the one thing that troubles me is that the green wire on the main harness goes straight into the amp. is that ok?

also any idea what that other green wire with the round tip thing goes to?

 

see if that other green wire is +12V relative to a chassis ground... if it is, cut off the connector and tape it up so it can't short and blow whatever fuse its on (fuse 8 if its the wire I think it might be).

 

it read 13v. i cut and taped it. what was it?

so most likely its the radio itself and not the wiring thats causing the issue?