My '92 190E w/165,000 miles, just quit at a stop light, and would not start, even though the idiot lights were on and windows would go up and down. A jump got me started. Took battery to a parts store. They said it tested good, but was very low, took a 20 min quick charge. Took it to my mechanic who is methodical. He loosened and cleaned all the connections, even engine ground. He found part of the wiring harness routed too close to the exhaust manifold and had a toasty wire. He replaced a section of wire, soldered it, and rerouted the harness. He said alternator tested good UNTIL you put a load on it, like aux fan for a/c + headlights + interior fan...took it below 12V output. He says its the voltage regulator, which is inside the alternator. He doesn't know if it's a simple plug and replace or the soldered kind. Bosch W0120-485022. Looks original to car. Anyone know if it's a plug-in VR? Are we on the right track? Should we be looking at the year-old battery? Thanks for any light you can shine.