I have a 2002 450 foreman 4x4, the other day the 4 wheel drive started acting up. I can be going through deep snow in 4x4 and it will just randomly lose 4x4 and I have to turn the key off and back on for it to work again. it has a new battery fully charged. any ideas what it could be?

 

The 450’s 4WD system has a “fail safe” that drops the 4WD out at over a certain speed if it detects the front crown wheel going faster than it should in relation to the prop shaft, why, I don’t know as they are fixed together so the only reason it detects this signal is if the sender units are faulty. On late 450s the 4wd light blinks a certain number of times to indicate which sender unit is wrong.

 

it does it none stop I cant keep it in 4x4 it just constantly turning off

 

Does the warning light start blinking after failure? If so the number of short blinks before a long blink indicates a fault code. If not, it could still be a loose or shorted out wire. I would start with the ones from the diff solenoid to the ECU. With the engine running and 4wd engaged, wiggle the wires and check if the 4wd drops out, then try the speed sensor wires, the ones with a round black plastic sensor on the diff. Next the handlebar switch wires etc. The system is very over complicated with sensors to check if the engine is running as well as the speed ones, the simple cable and lever of the 420 works just as well.

 

Have you made sure all tires pressure are correct? Yes Ino this is weird but I have had tire psi be off an cause 4x4 to fail.. just check and easy fix.If one tire psi is off this can cause 4x4 to kick off because its make tire an different size.Good Luck

 

Found the problem. It was blinking 6 times which is a charging problem. Turned out my voltage regulator was gone put a new one on and works great again