86 VW Golf Stopped Running-Electrical?

86 VW Golf 5 speed - took out Alpine radio/CD player capped ends, car will not start. This is the second vehicle this has happened with, same thing with a VW Jetta 86 also. Have checked the battery, spark plugs, fuses and even used probe to check ground wires which came up negative. wiring in dash for radio shows 2 red wires, 2 black wires and 2 brown wires, not sure why there is 2 red/black. Does any one have a diagram of what it should look like?