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
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.
There is a resistor pack operated by the fan switch. It has failed. You need to replace it.
For a Pontiac Montana the battery is a group 78. Follow this link for dimensions.http://www.rtpnet.org/teaa/bcigroup.html