Burning Headlight Relays
 

Hey All-
I made the switch over to the "Whiter Whites- Brighter Brites" headlight relay system about a year ago. Works GREAT but........I keep going through relays and I can't figure out why. Can anyone out there tell me what to look for as a cause to the failed relays. I'm using the run-o-the mill 40 amp relays you get at most auto parts houses. The "juice" is supplied by another starter relay wired in series with the original starter relay that is switched by the ignition side of the of the original starter. I used 12 gauge wire for the light circuit. I'm baffled and going broke buying relays.
Thanks, Bob

Make sure ALL your grounds are in good shape.

Steve

Thanks Steve! That's where I will start.
Bob

I don't quite understand all the starter relay stuff involved in your headlight wiring, but if the 40 amp relays are sending power to a starter relay, then thats your problem. The 30 and 40 amp relays are designed for lighting loads, not a large inductive load like a starter relay.

If the contacts of the 40 amp relay energize the other coil of the large starter relay, everything is fine. But when the 40 amp relay drops the voltage to the starter relay, the starter relay coil will de-energize and send a "kick-back" voltage backwards through the 40 amp relay contacts. This is a large enough spike to damage the 40 amp relay over a period of time.

If you happen to have it wired this way, you could put a diode across the starter relay coil. This would suppress the kickback voltage.

Hi Dave-
I'm sorry, didn't do such a good job of describing my system. I have the 2nd starter relay in series with the first one then to a fuse block which is where the headlight relays get "juice". The Fuse block is not energized until the ignition energizes the 2nd starter relay.
Bob

That sounds ok, but a little unconventional. There really is no reason to have the 2nd starter relay energizing the aux fuse box is it?

I really do not have a definitive answer to your problem, but I wonder if they relays would last longer if you did take out the 2nd starter relay and ran the aux fuse box hot all the time.