Law enforcement tells TMZ ... the reality TV star was arrested in Sin City early Friday morning around 1 AM.

Corey Harrison tells TMZ ... he had flown back into town from Minnesota late Thursday and went to check on a few short-term rental properties he manages in Las Vegas.

Corey says he was driving and got pulled over, with the cop telling him it was because he was swerving. He says the officer asked him if he was drinking and he told the cop he had one drink 7 hours ago on his flight home.

Corey says the cop asked him to step out of the car and take a field sobriety test. He says he took the test and asked to take a breathalyzer, but claims the cop told him the breathalyzer was broken.

From there, Corey says the cop handcuffed him, explaining he had failed his field sobriety test. He says he was then hauled off to a police station where he claims another breathalyzer was not working.

Corey says police informed him he would be held in custody all weekend if he did not take a blood test ... and he says they took a blood test and cops released him about 8 hours later.