So it's a t-rex pump? i wish i could help, i would just check for voltage in my harness in the back under the bumper, but i dont have a t-rex, and i have no knowledge how they hookup, my horn went out too once, it was because i blew a fuse trying to hookup a stereo, i had to get my brother to do it before i burnt anything else......hope you find it, let us know, and i'll ask around.
Oh, my friend relocated battery in trunk, he had one of those little batteries, whatever they are called, but accidentally hooked the terminals up backwards and fried some wires in his harness, just a thought, im sure you would have known better, because you would smell burnt something.
__________________
Police package 5spd 90 Lx, Stock original motor, 3.27grs, BM fan, fms 10.5 clutch, D&D quadrant, and adjuster, ADS chip, 180 stat, mac cai, mac h-pipe, mac subframe connectors, ASP crank pulley, ripper shifter, 26x10.5 M/T sport pros welds. 246 hp according to analyzer
Race weight: 3,120
E.t-13.57 with 26x10.50's e.t. streets. 1.88 60'
mph- 99.92 mph