Maybe I misconstrued your description of "limp home." Usually what that means is that the electronic part of the ETA has failed and you are actually manually operating the throttle butterfly with the throttle cable. On cars with ASR, the EA function actually controls the butterfly with an electric motor on the side of the ETA. You are just moving a potentiometer with the cable and the computer decides whether and how much to actually open the butterfly. Here's a good example.
Mercedes M119 motor throttle body rebuild. Wiring replaced. - YouTube
Maybe your "limp home" was just a generic expression. Do you have an ASR light in the cockpit when you turn the key on?
In any case, DTC 3 under pin 7 points to the ETA, whether it is only a CC/ISC (non-ASR) or an EA/CC/ISC (ASR). The blink code reader you made is only good to read analog data, but there are a number of digital codes under that DTC that can be read with a more complex/expensive reader, like the Star diagnostic reader the dealer has. Many of us just try to determine if it's the original ETA. If it is, there's a good chance it's bad. If it's been replaced somewhere along the line (after 1996), then I would be reluctant to go out and buy an ETA.
The Japanese model could be an entirely different animal so I'm just going by what I know of the US cars.