Ignition light stays on with engine running at above idle speeds, and occasionally all the time. Fan belt is broken, or very loose, or worse, the dynamo brushes are worn out. Check the earth connection for the control box as well, on a Farina it is amongst the bunch of black wires thaat bold to the inner wing, under the bonnet stay. The bolts and its threads must be clean, no rust. Also clean the battery earth to inner wing bolt and wire. A faint light could be either a slack belt, worn brushes, or just light seeping in from other dash lights.
Fuel gauge and petrol gauge go up and down slightly when the engine is blipped. Suspect the voltage stabiliser on late models, (fitted to rear of speedo.)
Water temp gauge not working, probably the sender unit, try fitting a new one, (top/front/off side of cylinder head.) Poor connections will often cause high resistances, so clean up the connectors, often covered in green verdigris. WD40 will keep it clean in the future.
No brake lights, either duff bulbs or the sender unit is faulty. It lives in the four-way connector in the brake pipes, under the heater shelf, but above the starter. Before fitting a new one, clean up the connections again. Age will have made the connections poor. If the sensor is faulty, woth the ignition on, join the two wires; the brake lights should work. Put cling film oveer the master cylinder, put the cap back on, and unscrew the sender and fit a new one. Remove the cling film. The cling film stops the brake fluid from escaping by creating a vaccum in the brake lines. You only need to bleed the brake cylinder closest to the master cylinder to remove the tiny bit of air that will have entered the pipe. Make sure you swap the sender unit straight away because the more you leave it out the more fluid gets out. You'll end up bleeding the whole system anyway.
Nearly all the other light problems are poor earths. The bulb holders corrode inside. Clean them up with rolled up emery paper. Waxoyl and WD40 the hole, as well as the bulb when you fit it. The little spring behind the inner contact inside the bulb holder can rust away. Biro springs are ideal for repairs here. The front sidelights and indicators suffer this rust problem the most, those in the boot stay clean. Check the bunches of wire connectors each side of the front of the car that feed out to the headlamps, sidelights, and indicators. They are often very corroded inside, full of green verdigris. Small rolled up emery will clean up the insides, though they are cheap enough at autojumbles. Poor contacts mean poor lamps. Look out for the household screw connectors which means an inept DIY merchant has been joining wires. These are useless in a road enviroment, as they corrode very quickly. You must solder wires and fit correct connectors if you want reliability.
No Horn can mean the fuse has blown, or the relay on late cars is kaput. Water inside the horn will stop it from working. Check inside for rust, often a cause of non-operation. Also check the fuse holder contact. Are the bits of metal the fuse contacts with clean? Verdigris again will cause poor contacts. WD40 will keep it clean once polished up. The fuse holder lives next to the control box.
Radio Interference can be cured by fitting surpressors to the plug leads, the coil lead, and to the distributor feed wire from the coil. If you can hear a whine the alters with engine speed, fit a 1mf surpressor to the 'D' wire from the dynamo, or the thick wire from an alternator you have fitted. If it still crackles, check the outer wire of the coxial aerial cable is earthed both ends, and fit the radio into a steel box to screen it. If you use suppressor leads to the plugs, (non-wire type,) expect problems after 18 months with starting. The carbon string inside gets damp easily.
Slow Wipers will be caused by poor lubrication inside the cable conduit; a wiper gearbox needing grease; poor earth contacts to the inner wing; worn out brushes; insides of the wiper switch worn out of breaking up, (this happens to the lights switch as well.) This is all supposing the battery is fully charged.
On self park wipers, the position of the metal cap ont he gearbox is critical. It needs to be rotated till the arms park as you want them, then the cap screws tightening.
Indicators that do not cancel usually means that the steering column unit needs cleaning up. A good wash in WD40 works wonders. If the plastic rocking levers are worn, you will just have to remember to cancel yourself, or find a good second hand unit. Fast flashing on one lamp only means the other has a blown bulb or a poor earth. Very slow, or very fast, or just staying on and on flashing means the flasher unit has had it. First thing to check if there are no flashers is the fuse.
No sidelights may mean the in-line fuse behind the battery, in the wiring loom, has blown, or is just not contacting well. Clean it first. It is inside the plastic torpedo with a boyonett connector cap.
Fuel gauge reads sometimes, but not others. Check the connector and earth lead at the tank, (inside the boot and under the floor, above the rear axle.) Old age can mean the wire rheostat is worn out, (the sender unit) and no reading. Half fill the tank, and rock the car hard, and this may dislodge a sticking float.
Car stops, or fails to start, and you trace no fuel delivery to the carb. On electric pump fitted cars, it is the points in the fuel pump that are burned out. New ones are available, but tapping the pump may get it to work till you get home. Even cleaning one half of the points on the kerb stone may work, (the other half of the points need major stripping of the pump.) A loose plastic nut on the wire connection can give an odd start-stop motoring. It lives underr the fuel filler cap, behind the black cardboard trim, in the boot. New ones are expensive, points are about $3, #5. Do read up the manual because changing the points is not straightforward because the pump stroke can be affected. On mechanical fuel pump cars the diaphragm may be split, buy a kit to fix. But really now, did you put gas in the tank?