I just replaced the transmission control unit on my gf's 1990 Honda Accord and now the car won't start!

Prior to the replacement, the car was running fine with the exception of the green "S" light would come on from time to time and the car would no longer accelerate normally (as if stuck in 1st gear). After seeking support, some suggested it was probably the TCU. So I went purchased a new "used" one (which the seller said was working) to replace it.

I took out our old one and replaced it with the new one and now our car won't start.

I even put back the old one (just plugged it in, didn't put it in the bracket) and the car won't start with the old one either.

So now are car won't start!

Any ideas?

By the way, during the process I unplugged the ECU as well because I was replacing the heat blower motor and needed to get the whole bracket out of the way. Could that be the problem?

 

Does any one have any ideas? We really could use the help.

Again, all I was dong was replacing the TCU.

• Before I started, the car was starting fine.
• When I went to replace the TCU, I also disconnected the ECU (because I was simultaneously replacing the heater blower motor and the TCU/ECU unit was in the way).
• When I was done replacing the TCU, I plugged everything back in.
• Then the car wouldn't start any more.
• I even tried putting the old TCU back in, and the car still wouldn't start.

Here's a video of what's going on in the car's display. You can also hear the car trying to start in the background.