It giving you some kind of code. Have your codes read.
time for a new battery or just the cable is going bad
To reset the flashing security light in a 2001 Pontiac Bonneville SSEI, first, ensure that the vehicle is in the "Run" position without starting the engine. Then, leave the ignition on for about 10 minutes until the security light stops flashing. After that, turn the ignition off for 5 seconds and then start the vehicle. If the light continues to flash, you may need to check the key or the security system for further issues.
A flashing green light on the AC switch of the 2001 Montero indicates there is a situation that requires attention within the cooling system. The issue could be as minor as a loose connection to an outright system failure.
smack it with a hammer
light sensor
It is important to know why flashing lights come on in a vehicle. When a transmission light comes on it can mean that there the fluid is low, or that there are other issues.
A malfunction has been detected
it is in the manual says when this happens it is 02 sensor and if it is flashing you have a miss in your engine which can cause damage.
Flashing light indicates it is not in 4X4 but is attempting to. light should stay solid when 4X4 is locked in. Are you trying to go into 4lo or 4hi?
sell it
This must be taking to a qualified person to have checked out.
A flashing over drive off light indicates that a malfunction has been detected with the transmission - get it checked out by a professional as soon as possible