I have a 91 honda accord lx. The "s" light constantly blinks and the car shifts from 1st to 3rd so I dont have 2nd or 4th unless i put it in manually. The TCU gave me error codes 7 and 15. I removed the TCU and looked at the circuit board and there was corrosion. I ordered a rebuilt one and installed it today but it didn'y fix the problem. My speedometer also occasionally goes down to zero when I'm driving and my radio sometimes will not come on when I start the car. Could it be me ECU? Any suggestions would be great. Thanks!

TxGreaseMonkey

1. Check all under-hood and under-dash fuses with a test light or multimeter.
2. Clean main VSS/ECM ground on the thermostat housing.
3. If the odometer and trip meter work but speedometer does not, then the problem could reside with the speedometer or the printed circuit board.
4. Check Vehicle Speed Sensor (VSS).

Make sure your transmission fluid has been recently changed. You might also want to look into AutoRxing your transmission, if you think it's not too far gone and that it might have developed varnish or sludge. I recommend synthetic ATF for healthy transmissions. The benefits are numerous.