Did you check the fusebox?

 

Do you have a bentley manual? If so start looking at the wiring circuits and see what is common to the problems.

 

Sounds like whatever the stereo is tapped into can't handle the load the radio is placing on it, or however its installed is mixing powers or grounds up and causing the cross system problem.

 

had a similiar problem and the voltage regulator could not handle the new load from the newer system. had alternator built up and replaced regulator thats on the alternator. wipers, lights, everyting started working right again.

 

Check the fuses first and foremost. Also check to see where they tapped the ignition wire for the radio since 1990 G60's didn't have switched power in the radio harness. There is a good chance they made a bad choice in wires to tap for switched/keyed power for the radio.

 

^ that is exactly what I was going to say.
I am dealing with that right now, too.

 

Thanks a lot everyone i have checked all fuses an relays everythings cool. but imma go tackle the harness now with the ignition problem. i really dont mind not having a radio to much because i have no Cat or muffler. i like it extremely loud :beer:.

 

Nothing like a loud G60...

 

Tractor with a little hoover vacuum in there, sounds good!