Ready for a multi-part, multi-link, answer?
So yes, as you've probably guessed from the manual, the "radio" that you see in the dashboard isn't a radio at all. It's a control head with buttons and a display. And a cassette or maybe CD player. The tuner and amplifier are housed in a separate unit mounted under the dash. And yes, if your speakers and speaker wires are good, but one side doesn't work, the problem is probably in that main unit. (By the way, is it BOTH right speakers, front and rear? If so, that's even more of a sign that it's not the speakers themselves.)
Post #7 here describes in text how to remove it.
https://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/199758-where-tuner-box-1992-brougham.html
In this YouTube video, the man making the video half-correctly describes the unit as an "amp." It does have an amplifier inside there, so fair enough. Anyway, he has already removed the unit from his car (because he's installing an aftermarket radio), but you'll get to see what it looks like, as well as a view of the connectors. Worth watching.
https://www.youtube.com/watch?v=HNLFrvvGdoM
This two-box setup was not something GM commonly used, but they did use the same approach in a few other cars. Most notably the '88-94 pickups. Here's a detailed post of someone repairing the problem in his Buick Reatta. Should be very similar to what you have.
http://www.reattaowner.com/roj/88-accessories/radio/198-radio-capacitor-replacement-instructions
So yes, as you've probably guessed from the manual, the "radio" that you see in the dashboard isn't a radio at all. It's a control head with buttons and a display. And a cassette or maybe CD player. The tuner and amplifier are housed in a separate unit mounted under the dash. And yes, if your speakers and speaker wires are good, but one side doesn't work, the problem is probably in that main unit. (By the way, is it BOTH right speakers, front and rear? If so, that's even more of a sign that it's not the speakers themselves.)
Post #7 here describes in text how to remove it.
https://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/199758-where-tuner-box-1992-brougham.html
In this YouTube video, the man making the video half-correctly describes the unit as an "amp." It does have an amplifier inside there, so fair enough. Anyway, he has already removed the unit from his car (because he's installing an aftermarket radio), but you'll get to see what it looks like, as well as a view of the connectors. Worth watching.
https://www.youtube.com/watch?v=HNLFrvvGdoM
This two-box setup was not something GM commonly used, but they did use the same approach in a few other cars. Most notably the '88-94 pickups. Here's a detailed post of someone repairing the problem in his Buick Reatta. Should be very similar to what you have.
http://www.reattaowner.com/roj/88-accessories/radio/198-radio-capacitor-replacement-instructions
