Either there is a wire lose or the flasher relay is not working right or lose in its socket.
It is located in the fuse box under the plastic cover at the bottom of the dash. Make sure you don't have any burned out bulbs, as sometimes that will cause the others not to flash.
'How do you change a fog light in a 1996 Pontiac Bonneville? ... How do you
pictures of how to change front signal bulbs on a 2004 grand prix pontiac
On some, you can get to the back of the light assy and take the bulbs out. If not, the assy has to come off
Because it is
Headlight bulbs, high and low beam, parking light bulbs, signal light bulbs, brake light bulbs, dash light bulbs, interior light bulbs, plate light bulbs, etc.
Start by checking fuses Then check the light bulbs Some Bonnevilles have “Cluster lights” These should be checked by a dealership or a qualified mechanic
On some cars the bulbs screw in from the rear and you have to take the light assy off to get to it.
is your e-brake on?
Have vehicle scanned to determine the problem
"http://wiki.answers.com/Q/I_have_a_1999_pontiac_bonneville_and_the_monitor_light_system_is_on"
Because it is broken