For a while now, randomly while driving, the voltage surges to the 18V mark on the voltmeter, and goes back. During these surges, the headlights brighten, blower fan speeds up, etc. Lately, these surges blew out both the high and low beam headlights while they were on.

New battery was installed, and kept the surges/CEL off for about 100 miles. However, they are back. Today, I swapped the alternator, and the surges are still present. I am thinking it's the voltage regulator, which is still evidently in the ECU.

Has anyone dealt with these issues before? Was it the regulator?

Thanks,

Stephen

 

Regular voltage with engine running is around 13-14 volts. I would say replace the alternator aging to make sure you didn't get a faulty part. Next it will be a wire issue or the computer.

 

They checked the new alternator along with my old one at AutoZone before I installed them, and they both "passed" on their test. Because the surging only happens every once in a while, I can see how they would have passed. However, having two alternators with the same, intermittent problem, seems highly unlikely.

I am wondering if it may not be a wiring issue, but I don't know where to look first.

 

Test to see if you have continuity from each wire to the computer pin. Check the FAQ for the wiring diagrams.