Question1989 Toyota Tarago van, 8 seater, 5 speed manual, 3y engine-4cylinders. Red light for battery and water comes on when running. Alternator tested by experts-good, yet, headlights do not brighten or dim in relation to idling faster or slower. Water level good. Battery fully charged. Checked fuses under dashboard-ok. Could it be some form of a relay related fault? (if relevant) Although, no other problems, have stopped driving it at the moment. Please help-confused.
AnswerOn some of the older Toyotas there was an issue
where the alternator would send a signal to the ECM
saying it wasn't charging and yet it was.
To be absolutely sure; while the engine is running
attach a multi-meter to the battery and it should
show at least 13.5 volts. Now turn on all the lights,
rear window defroster, heater on high and watch the
voltage on the meter if it falls down to less 12.5 or
so the alternator is bad.
