interior and exterior lights "pulsating" while idling...

[msowers]

I have a 2000 Explorer and recently I noticed that the lights, interior and exterior, were "pulsating" while idling. So, since I just recently purchased it used from a dealer, I took it in thinking that maybe the alternator, or some part of it, was going bad. They thought the same and replaced it. The problem was still happening. So, the dealer put another alternator on and replaced the battery as well. We're still having the problem.

Does anyone have any ideas on this? My dealership and I are both stumped. I'm planning on making an appointment at the local Ford garage, but was curious if anyone else has seen this.

Thanks!

[Fordexplorer157]

You would think it would be a voltage problem. Make the dealer pay for all repairs that the Ford Dealer has to make. That is very odd

[wseng]

Does your Explorer's idle speed fluctuate too? I noticed the same problem with the lights, but only on a cold start. For my car, I think its the weird idle speeds that's screwing with the electrical system. Dont know if that little bit of info helps you any...

[cat5]

Could it be that something is putting a heavy load on the electrical system, pulling the voltage down while idling? AC, high-power audio amp, Rear defroster, a short?

[oldfordguy]

I have a 78 f150 supercab 4wd that does the same thing. I replaced the alternater, regulator, went through much of the wiring, all to no effect. There dosent seem to be a problem keeping 2 batteries charged up, so I just left it. Good luck fixing it, and if you do, please let us know what it was. Many fords seem to be aflicted with that problem.

[Opera House]

One problem that it can be is the grounding from the engine block to the car bady. Remember that the engine is basically isolated from the body by engine mounts, the only electrical connection being a poor one through the bearings. In older vehicles these ground connections can go bad. I heard of one newer Explorer where the ground screw was never tightened. Try an extra ground wire from the b;ock to the body. Another problem has been corrosion on the 15A fuse that supplies the alternator regulator.