Any parts store will scan your computer for free. Autozone, checkers, pepboys, Advanced, possibly napa. But it has to be a 96 and newer. All of the obd2 ports have the same 16 pin connection (government mandate) if it couldn't read, it's problly a "link error" which could be several issues. No power to the link, either a fuse, or ECM fault. Granted the pocket scaners won't read in this instance. But if you pay for a code pull (most Shops are still free) they'll hook up there $5,000.00 scanner which supplys it's own power and should bypass the "link error" issue.
TLCA # 20314
84 Hilux, 22re Conversion, 63" chevy rears, Rears up front, Bobbed bed, duel e-lockers, 5.29's, 35" Ground Hogs
Step by Step Bed Bob