Flashers don't work in a 2000 Pontiac Grand Prix. Don't have a book or wiring diagram to backtrace source of the possible problem.

Howdy anonymous,

Beyond the always FIRST STEP of blaming the "FLASHER"....
(see rockauto example $ below)

There immediately follows moving on out to the light bulbs and checking they (EACH & EVERY) work...

Then & only then do you start "BACK-TRACING"

I always recommend getting REAL FACTORY support documents but luckily BBB Industries has FREE documents for popular USA models: and TECHNICAL SERVICE BULLETINS...
(foreign & domestic... (registration required... real documents))

Go to the wiring SCHEMATIC... You will find REFERENCES to both BATTERY & GROUND...

It would be really helpful to know... WORKING STATUS?

Tail lights
Brake lights
Left signal
Right signal...

If Tail lights and Brake lights work... you can
pretty much forget about BACK-TRACING altogether...

Start with your FLASHER power source and move
immediately into the "multi-contact flasher switch

Cost... Rockauto
http://www.rockauto.com/en/catalog/pontiac,2000,grand+prix,3.8l+v6,1359345,electrical,flasher,10139

Details
More Information for ACDELCO E1958E

FREE wiring & TSBs
BBB Industries Premium Alternators Starters Power Steering Products

Hope this helps

Toner Tracer... (BACK-TRACER: not a novice tool)
Extech TG20 Wire Tracer and Tone Generator Amazon com

Carnac the Magnificent