Land Rover Repair: 1996 Range Rover 4.6 HSE

Question
John,

My Range Rover has a voltage drop about every 15-18 seconds when running. I notice it most if I sit idling for any amount of time, most notably in the green odometer display as it dips, along with a small pop in the speakers. I can sit in driveway with door open and see the dome light dip considerably as well. It does this even with lights on or off, A/C on or off, etc. Can you suggest what else I should be looking for? I am pretty proficient, having reasonable understanding of electrical systems and repairs.

Thanks,
Michael

Answer
What you should do is put a clamp on current probe in the power line and determine if the voltage drops because of a momentary current surge, or because of momentary alternator failure.  If it's a surge you don't have too many heavy consumers of power to check.  If alternator cutout, replace it.  Imminent breakdown of the fusebox connectors is also a possibility