99 4Runner Issues

Hello all, new guy here with big trouble. I have a 99 4 Runner with a check engine light on. I got the fault that was 1870 ( nuetral safety switch) I replaced the switch ($220.00) and the light is still on. I reset the switch and drove it about 25 miles. The light did not come on until I stopped cut the truck off, cranked it up and put it in Reverse. then the light came back on. I get the same fault. 1780. I don't know what to do. I need to get it inspected. (NC law) It will not pass inspection with a fault code. Can anyone tell me what to try next? Well I found out what I need. I will ask anyone who knows where I can get a ECM for my 4 Runner. They want over $1000 for a new one. Can anyone give me a web page or a point of contact to get a used or reconditioned ECM? My 4 Runner has over 180,000 miles on it. I really don't want to spend that much money on it. Not for that anyway. Thank you in advance. JEFF