I was able to acquire a 1987 euro 240 gl B230k carburated engine with a 4 speed OD. My problem is the OD switch does not switch on in the dash and upon further testing, the "Drive" only shifts up to 3rd gear only. Transmission is the Aisin AW 70/AW 71 type. Where is the relay switch located? The reverse light is working so I assume there is power running since the fuse of the OD and reverse light in interconnected.

Another question is, if the OD does work, when the OD button on the shifter is depressed, does it lock by itself or does it work like an ordinary momentary switch?