I replaced my alternator on my 2002 Volvo S60 2.4 non-turbo, that had failed about 6 months ago. After replacement when the car would start the "service electrical system" light would flash for a second then turn off. Yesterday on the freeway the car shook and jerked and the "Over Voltage Pull Over Safely" light came on. My question is; do I replace the voltage regulator or the alternator? The car would shake, the ABS failure light would flash on and off and the speedometer would go crazy.