Whenever the charging system has a malfunction, the "brake" warning light comes on as well as the "charge" light on Toyotas. Don't know why they did that. I suspect you have an alternator malfunction. If the previous owner swapped in an SR-5 instrument cluster and did not change the oil pressure SWITCH to an oil pressure SENDER, it can ruin your gauge, I hear. I upgraded to the SR-5 cluster in my base model 86 4Runner and changed the switch to a sender and all was well. I notice that the fuel gauge holds its reading even after the ignition is turned off.