A few days ago, all the dash warning lights lit up and stayed on. This includes the check engine, battery, and brake lights. When I pull up on the parking brake handle, I can see the brake light gets a little bit brighter. Before this occurred, I could smell a plastic burning scent. I looked under the car in case I snagged a plastic bag on the exhaust and found nothing. When the car was hoisted for an oil change, still saw nothing underneath. It isn't the smell of engine, tranny, or automatic fluid smell dripping from a leak onto the exhaust (and I can't see any smudges left on the exhaust from the remnants of the burn off). It isn't the smell of a dragging brake pad and I've touched each wheel and found none of them hot (beyond those of the other wheels caused by normal braking). It isn't the sweet smell of leaking coolant or the smell of sulfur from the exhaust. It very much smells like a plastic bag burning up on the hot exhaust but I can't find anything on the exhaust manifold (well, okay, some oil) and pipes. Also, sometimes the scent occurs when I've only gotten a few blocks from home.
Before this, the check engine light came on occasionally. I could be driving at it was off and then came on. Or when I start the car it stays on. I've had it into the dealer and a car shop 4 times and they could find no code to read to indicate what was the problem. You can hook together 2 black connectors under the dash by the ECM (engine control module, or maybe it's called the MPFI module; i.e., the computer in a bracket mounted vertically under the dash near the fuse box). This has the check engine light flash to tell you an error code (long flashes are ten's digits and short flashes are one's digits). It looks to flash out a code of 35 which, I think, means a problem with the EGR valve. Yet I've been driving the car without problems for 3 years with this symptom and the car shops can't read anything from the computer.
I tried the trick of disconnecting the negative cable on the battery to see if the computer would reset. Nope, no go. The only thing changed recently before this all-lights-on problem was to replace the 2 fan belts. I started wondering about the alternator and/or battery. The following are the voltages measured across the battery's terminals under various conditions:
#1 - When NOT running, the battery's voltage is 12.2 volts (which is close to 6 cells x 2.1 V/cell = 12.6 V; it's a 6-year Delco battery that is now 4 years old). #2 - When I first start the car, voltage drops to 10.6 volts (which is probably due to the amps getting sucked up by the starter) and then comes back up to 11.8 volts. #3 - When running at idle (