Took the boat out yesterday. After loading and getting in to drive off I realized I left the keys in the boat ignition. I hit the brakes and threw it in park to go get them. I was on gravel and saw that the passenger rear tire locked up instantly with very little braking pressure from me and the driver rear tire did not lock up. I tried it again three times and it did it every single time. This is the first truck I have had with ABS so Im not sure if something is wrong. Any ideas? Thanks in advance.

 

Sounds like you could have the same problem we just went through on my sons truck. The axle seal started leaking and soaked the shoes and that set of duals would lock every time. Either that or your emergency brake lever could be hung up from backing in the water and partially holding the brake on.
You need to go in and see before something gets ruined.

 

Thanks I will pull it apart and check.

 

I second the wheel seal. Either that or you have a wheel cylinder leaking. Let us know what you find.
Tom

 

As the others have said, a visual inspection is necessary. Another possibility is if the automatic brake adjuster on that one side is not working properly.