I was having the same wiper issue on my '94 GC ZJ, but in the end the cause was different. I followed the nice guide here, but turned out my module was not burned and all other components looked or checked ok. (years of electronic repair exp).
So If like me you still have the delay problem after checking/replacing the delay module, there's one more thing you might check if your wiper delay isn't working and the wiper module is ok.
Reseating the harness connector to the main ECM module. (located on the firewall passenger sided in the engine compartment on my '94 ZJ). I had two issues with my ZJ. No delay wipers and an intermittant problem with #7 fuel injector. I concidered them totally unrelated. But while working to solve the injector problem, I checked the injector - ok, checked the injector connector - ok, checked the wire harness -ok, reset the large connector to the EMC module, injector worked again. Days later I found the delay wipers that hadn't worked right in a year, even after tearing into the wiper module, were once again working. Both issue were apparently due to a poor connection at the EMC. The wipers have been doing delay again for a couple of months now and I now and I hope they decide to keep working from now on.