Assuming you mean the Daihatsu's ignition timing, the on-board computer should control the timing. If this is out of whack, you'll find the car could be difficult to start, will idle poorly, use more fuel than it should, be down on power and may even overheat. Or all of those things. For reference, the correct timing for this engine is five degrees before top dead centre (+ or – two degrees) at idle. It can be checked by a workshop to verify whether it's correct or not.

If you're referring to the engine's valve timing, that's a different thing altogether. You need to reset the valve timing whenever you change the rubber toothed timing belt to avoid catastrophic damage to the engine. The valve timing of the car should not change between belt-change intervals, but if it has, then the damage has probably already been done. Again, for reference, the two camshafts need to be lined up with their respective timing marks, along with the crankshaft in its correct position before the new belt is fitted. This is not a simple job for a Saturday morning in the driveway.

If the ABS and overall braking system is working properly, then the warning light you’re seeing is probably being caused by a sensor or part of the electrical circuit involved in controlling the ABS. An electronic scan of the car’s on-board computer should give you an insight into what’s wrong and you can work forward from there. Simply replacing bits and pieces in the hope that they fix the problem is often a very time and money consuming way to go about this. Most workshops will be able to scan the car and interpret the fault codes.

What the mechanic told you is rubbish, there has clearly been a change in the way the engine is running, and that suggests there’s a problem. Changing the spark plugs, they’re located in the cylinder head, and the spark leads is a good idea. If you’re not sure take the car to an auto store and they will show you the plugs and leads and supply you with replacements.