Report "I have a 2003 lexus ls430. every time i get in it it wont start. it acts like the battery is dead but when i hook it up to another battery(even if the other vehicle is not running) it cranks up fine. also when i pull up to a stop sign it will shut off. i think it needs to be idled up but my question is, could the alternator be bad? i cant remember, is it possible to disconnect the alternator to test to see if its the starter? thanks"