Hello! my battery and exhaust warning light sometimes flicker at high rpms or high speed (60 mph+). Never at low speed or low rpms. Does this indicate that I need a new battery, alternator, or alternator belt? All of the above? thanks!
I have a BMW built year 1988 in Japan specification, that also has such a warning light for the exhaust, or more precisely to say for the catalysator, when that gets glowing hot. I explained the details here with pics https://minitrucktalk.com/threads/exaust-temperature-sensor-replacement.18425/ Maybe just the temperature sensor wires, otherwise check the cat. Battery light: when the engine is running the alternator produces normally enough volts to supply enough power for the engine, lights, aircon etc and to recharge the battery at the same time, so it cannot be the battery.. Check the volts while driving, I have in the cigarette lighter a "Cigarette Lighter USB Charger with Voltage Display", cheap and convenient to check the volts while driving. check the belt tensioner for the alternator, if that is all o.k., then it could be the brushes for the voltage regulator in the alternator. Maybe Yokohama motors has them listed or cpl. alternators https://yokohamamotors.net/page62.html But first check the alternator belt tension, maybe slipping.