Hello everyone, I have a 1990 Honda Accord LX. For the past few weeks it has been doing weird random stuff, i.e., wouldn't shift down into 1st and the speedometer stopped working but then worked again. Now the S Light has started flashing and the car will only shift into 2nd and 3rd.
About 2.5 years ago I replaced the TCU (transmission control unit). I bought a used part from a junk Honda off eBay, but it was a factory part. The car has run great until recently. I also recently replaced the speed sensor. That fixed the speedometer issue but the S Light started flashing about a week after that. I don't think the speed sensor caused the S Light to flash and don't even think the speed sensor was bad. I think it was all random, like everything else that has been happening. My question: It behaves with the same symptoms that happened when I replaced the TCU before 2.5 years ago. Would it be likely that the TCU is bad again, just coincidentally (especially since it was used), or is this something that just doesn't go bad often? Would it point to something else being the problem? I could buy another TCU and replace it but I don't want to waste money if it's not likely to be bad again.

 

Check for engine and transmission codes. This thread has a link on how to check them.

https://www.hondaaccordforum.com/for...threads-40780/