battery function is only to start engine. then its up to the alternator to produce enough electricity to power up all the different units in the car. Eg. lights, radio, a/c comp, wiper, window and etc. Unless u've replaced the alternator for a less-than-original spec alternator into your car, then your car's electrical needs are FULLY avai. For original cars, electrical current is never pulled directly from the battery, unless you've modded it before by installing an extra power cable bridging the alternator with the battery. this is not advised as it will overload the alternator and the lifetime of it would be reduced.
headlight needs current to power up, that's why it'll load up on the alternator. but when it does this, the TB sensor is supposed to recognize it and increase idling speed to compensate for extra load(notice that timing belt is connected to alternator ). When it fails to do this, then the alternator would be working VERY hard to power your headlights affecting your idling speed. the reason why you're experiencing decrease in idling for only the headlights is because contained therein the TB sensor includes responses for a variety of units Eg. power steering, aircond, headlights, brake servo. however, unfortunately you must replace the entire sensor instead of pinpointing the exact defaulted function (in your case the headlights).
what you can do is to ask ur mechanic to run a simple test. Dislodge the socket from the TB sensor and run your headlights. if problem persists, then it's not the sensor. BUT if problem vanishes, then jackpot !
TB sensor for Mitsu engines are easily avai (i was told) in chopshops. Reason is because the sensor itself can be taken out and sold separately without the TB. I was unfortunate coz Mazda TB sensors are one-piece with the TB and i had to buy the whole thing. It costs me a good RM400 thereabouts. I assume that since you're only looking for the sensor, it'll cost less than that.
Don't worry, your problem is common in many cars and if you google TB sensor+idling speed+headlights then you might find more interesting information.
Above all, HAPPY HUNTING !
headlight needs current to power up, that's why it'll load up on the alternator. but when it does this, the TB sensor is supposed to recognize it and increase idling speed to compensate for extra load(notice that timing belt is connected to alternator ). When it fails to do this, then the alternator would be working VERY hard to power your headlights affecting your idling speed. the reason why you're experiencing decrease in idling for only the headlights is because contained therein the TB sensor includes responses for a variety of units Eg. power steering, aircond, headlights, brake servo. however, unfortunately you must replace the entire sensor instead of pinpointing the exact defaulted function (in your case the headlights).
what you can do is to ask ur mechanic to run a simple test. Dislodge the socket from the TB sensor and run your headlights. if problem persists, then it's not the sensor. BUT if problem vanishes, then jackpot !
TB sensor for Mitsu engines are easily avai (i was told) in chopshops. Reason is because the sensor itself can be taken out and sold separately without the TB. I was unfortunate coz Mazda TB sensors are one-piece with the TB and i had to buy the whole thing. It costs me a good RM400 thereabouts. I assume that since you're only looking for the sensor, it'll cost less than that.
Don't worry, your problem is common in many cars and if you google TB sensor+idling speed+headlights then you might find more interesting information.
Above all, HAPPY HUNTING !
