A lot of RWD stuff had a high gear switch, but I very well may be wrong about this particular application. I haven't found a high gear switch in the wiring schematics for a 746 ecm which is what his car would have been originally equipped with. But, GM sometimes likes to put certain circuits in different schematics. For example; I was having issues verifying the generator turn on signal from the PCM on my wife's '00 Grand Prix and that circuit is not shown in any PCM schematics only in the generator schematics even though it is controlled by the PCM. I also had issues with the brake switch schematic for my car. Mine was originally a 5 speed car but somebody swapped in a 700r4 before I bought it and they didn't wire in anything except for the backup lamps. When I went to wire in the power wire for the TCC function the stop lamp switch schematics shown in the ecm schematics were incorrect. I don't have access to alldata anymore, but I suspect that the correct schematics may be found in the cruise control schematics. This may be the case here as well. I have verified that there is only one switch in the T5 and it is called the back up lamp switch. However, it may also serve as a 5th gear indicator as 5th and reverse are on the same shift rail and one 3 wire switch could be used for both functions. I'm not familiar enough with T5's to know if this is the case or not though. I'll have to do a little more investigating.