1990 2.5 ecu isa

On my yj the Isa isnt extending or retracting. The isa and coolant temp sensors are new. All other sensors test good. I've set tps according to fsm and replaced the b+ latch relay. I've ohm tested every sensor wire back to ecu plug and all test good. I've also tested all the grounds for sensors and main grounds. I'm thinking the ecu is shot. Problem is I can't find a new ecu anywhere. I've takin the ecu apart and don't see any visible signs of failure. With everything plugged in I've tested the voltage on the isa connector. I get somewhere around 9 volts on extend and 8 something on retract. Been a day or two since I tested it. From searching other posts I've determined that you have to have positive on extend and ground on retract to get it to move. Is the ecu not switching the polarity ? I've also removed the isa and bench tested it and it still moves w positive on one and ground on the other and vice versa. Has anyone sent there ecu off and had it rebuilt if so to who? Thanks.