singing GPR
 

I assume it means its dying or dead, but the GPR on my new truck has a high pitch hum/buzz when energized.

figuring it probably means its arcing inside, which can't be good for the GPs, i'm just going to disconnect the ground going to it for the rest of the summer and deal with it in sept/October.

any other thoughts/advice?

go with the western plow relay...handles 15 volts...stock GPR is rated for 12 volts...hth

FWIW, mine has done this since it was brand new. And it works like a champ. It's the GPR109 from NAPA.

well, that makes me feel better, nate. the PO did say that it was a 'new' GPR, but I took that with a grain of salt...

Mine does it every time. And the tone changes the longer I leave it on. People have tried to tell me it isn't making a good connection and will fail in no time, but it's been in there for 2 years and has never failed me yet.

were talkin you can hear this puppy singing in the cab right?

yep - before I start the engine, obviously though :-)

I also have a napa one, first one smoked.

does your sing?

Oh yeah.
I just noticed the singing and thought I had another bad one.

weird. especially since its all DC current flowing through it. if it were AC, I wouldn't think twice about it, but what would be oscillating in a DC coil? i'm going to sound like a dork here, but from my one college electrical engineering course, in addition to the inductor of the solenoid coil, the circuit would have to have a significant capacitive or resistive (or both) element to it to create a resonance. I couldn't think of where the resistance would be, then it hit me - the GPs, themselves! they're only a few ohms, but I bet that could do it. throw in some corroded connections along the way and I bet that's it. just enough oscillation to bounce the magnet off its endstop, probably...

and the changing tone would be from the GPs changing in resistance as they heat up.

mystery solved? ...maybe.

I guess that could make sense. I've often wondered where the tone was coming from myself. Like you said if it were an A/C current it would make sense. Like I say though, mine has done it since day one (about 2 years ago), the last time I checked all 8 plugs were just fine, and the truck started like a champ last winter in temperatures down to the negative single digits. So..... I don't know. If it fails again I'll just get the Stancor relay and be done with it, but when I got the NAPA one, I couldn't afford to wait. Now since the truck isn't my DD I could wait for the Stancor.