In Antwort auf:

The LED is used to blink out ECU codes
The Auto selector display blinks out the TCU codes.



NO! ALL codes will be displayed!

Okay, its not relevant for your problem so we go on...

If your transmission is in emergency programm, so it will be permanently at the 3th gear, do you feel so or does it shift well all four gears?

If it shift well, go on:

pull out the plug from the Sensor UNDER the distributor at passenger side, if no change visible, put it back

pull out the plug from lambda, it's deep under the distributor driver side, look at picture in

Gruess Roy http://roy-fuchs.smugmug.com/