Need advice on electrical problem

[srvivor71]

The last couple of times I pulled my truck into the garage, I noticed that the headlights and dash lighting was dimming and brightening right in unison with the engine speed. At an idle, they get very dim. Does this sound like a voltage regulator problem or a bad alternator?

[hayhauler71]

how is the belt tension?

[Prematuregrey]

Check grounds especially the engine, alternator (if equipped) and of course negative battery termination to frame. I'd pull them and clean them all and make sure they are on bare metal. Belt could be suspect as well as mentioned above.

[srvivor71]

I'll check these out today and see if it helps. I'll be very happy if it's something inexpensive like this.

[cdowns]

cleaning up all electrical connections and having nice clean shiny metal on metal conact aided by a bit of dielectric grease is a great help for the lights workin right

but the fact is that the lights will dim at lo RPMS cause that is the way they worked 40 to 50 years ago thay are not like 2013 stuff

[Wrenchbender Ret]

Put a load test on the battery. Sounds like a battery getting weak.

[srvivor71]

OK guys, once again, great advice! I replaced both fan belts and cleaned the ground to the engine block. There was paint at the ground site, so I ground it bare. Problem solved for under $20!