740 Turbo Overdrive Problems

Hi there I just bought a 88 740 Turbo Auto with 233000kms on it and I have a rather strange problem!
I noticed when I bought the car that the cable from the OD button on the shifter was cut just inside the plastic cover....I thought that it wuld be ok like that and the only bad side effect would be that I couldnt use the OD but 80% of the time when I start the car the OD arrow lights on the dash but then when I drive it the car doesnt shift out of 3rd gear which isnt great for highway driving :nono: but the rest of the time when I start it and the arrow isnt there the car drives perfectly.
So my question is:
How hard is it to replace the cable and how would I go about it?
If that isnt possible is there a way I can disable the overdrive?
Thanks for any help
Ste

It is common for the wires from the OD switch it break where they constantly "flex" when the shifter is moved. This break occuse under the console. The OD button controls a relay, push the button once and the OD is switched off and the lighted arrow appears on the dash, push the button again and OD switched on, light goes off.

I would simply check the wiring from the button to under the console and reapir it. My guess is that the "cut" wires are shorting and causing the irratic OD opperation. Repairing the wireing may solve this problem.

Good luck

Mine does that too. Thanks for the advice.