Jimmy Smog Fail Code

I have a 96 Jimmy that just failed smog in CA. The code that came up was
P1870: EVAP Ctrl System Small Leak Detected it also says on my smog paper. This vehicle failed MIL/Check Engine light due to a warning lamp failure. I saw on a few posts that that P1870 was a tranny code. Any help would be appreciated. My Dad gave me this Jimmy and he had the tranny replaced twice as well as the gas pump. :runaround:

1870 is a code usually related to TCC slippage, caused by a worn trans valve body, other things can cause it but that is the most common. The small evap leak can be just a bad or loose gas cap, after that it gets more complicated to diagnose and usually requires the use of a smoke machine to pinpoint the problem.