I have a 92 volvo 240 and when i step on the brakes, the entire rear cluster on the passenger side goes out. The rear window and left hand side get a little brighter as well during the brake applications.

Any ideas?

Thanks in advance

 

Bad Relay
possibly ..

my 740 needs a new relay ..... all kinds of funny stuff goes on when relay goes bad.

 

Check the earth (ground) connection for the unit that goes out.