Pontiac Montana was created in 1999.
In exhaust pipe before catalytic converter unscrew to replace
Replace the fan blower resister
Cam sensor location 02 pontiac montana 3.4
There is a resistor pack operated by the fan switch. It has failed. You need to replace it.
The question you ask is too involved for a proper answer. You need to go to a car parts store, and get a repair manual for your car. They cost about $16.00 Or, go to a Public Library.
For a Pontiac Montana the battery is a group 78. Follow this link for dimensions.http://www.rtpnet.org/teaa/bcigroup.html