I have a 98 montero sport with 3.0l v6. All the lights pulsate when the engine is running. heads, dash, tails, signals. I did some research and found chevy vans with the same problem and they corrected it by replacing the grounding screw and washer for the voltage regulator. Does anyone have any experience with this. I will replace the whole alternator if necessary, but it charges fine according to the gauge. any ideas?

 

I found this thread while searching for the same symptom that I have on my '03 Montero Sport. I'm sorry that there aren't any replies. Hopefully my reply will help bring some visibility to the thread.

 

I think you are on the right track with a bad ground.