Driving at both high speeds (70-75 mph) and low speeds (15-35 mph), switching the headlights on and off cause the car to stutter just a bit and the "Service Engine Soon" light to flash on and off in quick intervals. It does not happen all the time, but seems to be a majority of the time. Sometimes the "Service Engine Soon" light resolves itself after about 5-10 seconds and other times it seems as though it will not resolve itself and continue flashing.





I don't know if you need this information or not - Buick LeSabre 1987 with around 162,000 miles.


Any Ideas? We replaced the alternator and still have the same problem. Do you think it could be the voltage regulator? (I don't even know if there is a Voltage Regulator and where it is located if there is one).

 

Obviously Volatage problem. Check the belt tightness.
Check the voltages. 14volts charging. 12.5 volts not charging.
Get a meter..check the wiring.

Ignore the Service engine light,,, for now.
. .