98 Riviera with radio/steering wheel control issues

[buickowner98]

I have a 98 Riviera that has just developed a problem I'm hoping someone can help with.

The problem is the radio, steering wheel controls do not work, auto-headlights do not come on and antennae stays up.

I have checked all the fuses and all are good. Any ideas on where I can start looking?

Thanks for any help you can give me.