240dl Radio install

I am trying to replace the radio in my girlsfriends volvo 240DL wagon when I took out the old radio there was no connectors the wires came from the back of the stereo right into the ignition wiring harnes. I cut the wires and now i am trying to math them up. I believe that there are only 2 speakers I dont think there is an amp. I can get the 2 speakers workin but I am only attaching one wire positive. it works for a little while then cuts out if i remove the wites then put the back itll work again, So I guess im looking for the negitives. Also when the car is on I am getting a negitive signal on the wires that go to the speakers. Does anyone have a wiring diagram?


I have white with a blue stripe
and blue with white as the speakers
there is a solid blue
solid gray
solid brown
and solid green

Thanks

Andy

Please post a model year and I will try and sort it out for you.
All the 240s I have seen have the factory radio wires taped onto the harness but they end at a Molex white nylon connector just to the left of the center console.
To install a newer stereo you must have a minimum of 7 wires. Unswitched power (batt/memory), switched power (acc/ign), ground, and 2 wires for each speaker. You cannot combine the speaker grounds or the amps in the stereo will auto shut-down. (sounds like what is happening).