No high gear on 92 740 GL

It is a 92 740 GL wagon with turbo engine. It shifts into first and second fine, but never shifts to third. Makes it eat gas, not to mention the strain on the tranny from revving so high! I tried adjusting the kickdown cable a little both ways, but dont have a manual for this car, and don't really know any procedure to check if it is adjusted properly. Could it simply be that the kickdown cable is bad or misadjusted and so preventing it from shifting into high gear? (Yes, I have tried selecting/deselecting the overdrive button on the gear selector, has no effect)

And why is it called "kickdown" cable? It appears that it is just a mechanical way for the tranny to sense throttle position.

We got this used car with a spare tranny which the seller says is a good one...but just the labor to replace it would be a lot! Thanks Jim

A couple things to check First, are your shifter bushings worn? Does your shifter feel really loose? The shifter should snap into each gear position, if not you could possibly be putting the vehicle into second gear. Second, be certain you are not shifting into third gear and just not going into overdrive. The little arrow should light on your instrument cluster when you press the OD button, regardless of what gear you are in. If not, check your OD relay. It is the tall white relay located in the fuse panel behind your ashtray. If your kick-down cable was misadjusted it would affect all shifts not just third gear. The proper name for the cable is the Throttle Valve Cable. It is nick-named kick-down because at normal cruising speed if you extend the cable past it's detent, i.e.floor the accelerator pedal, the transmission will kick-down a gear (down-shift).