Intermittent Electrical Problem - Hilux Petrol Surf

[GraemeON]

I have an intermittent electrical problem. Vehicle engine starts ok for some number of times, then inexplicably, will either stop when slowing down or idling, and will not restart for a while, or after sitting for some time, will just not start. Starter relay appears to be locking in when turning on starter switch, but starter solenoid does not engage.

Additionally, the battery appears to go flat for no reason, which three mechanics have stated the battery needs replacing (so replaced twice with new battery, but has not solved the problem) Seems to indicate a battery drain somewhere, but no one seems able to find it.

Thanks for help

[Apache]

Borrow or buy a current clamp meter. Hang it on the battery +ve with the ignition off and see if there's any significant current flow (there will be a small amount - 10's of milliamps - if you have an alarm on or something such). If there isn't, there's nothing draining your battery.

Then start the car with the clamp still in place, and see how much current is going to the battery. If its near charged, it'll be somewhere <5 or 6A, if not, it'll be more. Make a note of the sign of the current (+ve or -ve - doesn't matter at this stage as long as you remember what it is)

Set around 1500-1700rpm and switch your lights on full beam. Check the current. If the sign is still the same, there is (probably) nothing wrong with your alternator.

The above will tell you if a) you have a short b) that your battery is charging properly, and might go some way to telling you what your fault isn't.