Yaris died while driving

The diode pack in the alternator could have gone short.

would that cause some of the bigger fuses to fail? I've not checked them due to lack of light. Fusible links gone maybe?

I'm fishing i know but this happened on an old Escort of mine years ago "fusible link" gone but no story told to me as to why.

Re-fit battery & positive lead. Touch negative lead - if big spark then your short is still there. Disconnect alternator and see if fault has gone. Repeat with other major electrical components as required.

Or connect something like a headlamp bulb between the negative lead and the battery; if the bulb glows near full brightness, the short is still there.

Chris

refitted battery tonight and everything seems ok. 13.9v at battery terminals with engine running at idle. Very odd.

only got what I think to be a normal spark when refitting the negative lead, nothing major and the car starts and runs AOK.

IIRC there was some problem on those with earth connections under the bonnet. It would be quite possible for a bad engine or ECU earth to re-make itself after being left for a while. So have a hunt around.

ok, thanks MrC

Three stages when checking the battery with a multi meter.

without the car running, with the car running and when you rev it up.

these should be distinctive voltages.

firstly the condition of the battery, secondly to see if the alternator is charging, which the voltage should indicate a rise from idle to 2000 revs.

I would have thought the charging voltage should be higher than 13.9 and go over 14V. and a fully charge battery is higher than 12v