I take it you have the 'check panel', aka 'ideogram', in your instrument pod? The one that's supposed to give a red light after checking the sensors and finding a fault or a green light if they're all are ok? If so then bear in mind that this was dropped for the later 70SX models because it proved to be too unreliable. The sensors used for low oil/ water/ brake pads are fragile and didn't stay working for long unfortunately. If you can find good sensors you could probably get them all working again, but also double check the wiring to the sensors too. Especially the low oil sensor as this is incorporated into the dipstick and the constant moving of the wires to check the oil tends to cause them to break.
If you're not fussed about having the check panel you can remove it and fit the brake pad warning light panel (the one with a pic of the car with tyre pressures and the oil warning light) in its place
Yes you are right about the panel I have. I would quite like to keep it as it came with the car. The wiring is ok, I am reasonalbly sure it is the sensors that don't work. The coolant one is bridged out and the oil light one comes on if I leave the oil light wires off.