Why relay placement is important

[Don_M]

Several months ago, I installed some LED driving lights on my 2017 Camaro, because while the headlights do a great job of FORWARD illimination, the projector beams do little for side illimination (like none). Surprisingly, Tractor Supply had a really good set of LEDs (of course the lights, 'Y' connector and wiring harness were separate), but they dramatically improved the 'side of the road' illumination.

One "drawback" was that the wiring kit had (for my application), way too much wire length (like 12 feet worth), but it was too cold and too cramped under the front of the car, so I just tucked all the excess behind the bumper cover, thinking it was safe enough and planned to "fix" it at a later time. That 'later time' turned out to be yesterday, after I discovered the lights, which I wired to come on with my parking lights, started flickering.

I had connected the wire to activate the relay to the side marker light, and initially thought that the connection was failing. So I took the easy route this time. Jacked the R/F corner up, removed the tire & fender liner. That way I could easily access the extra wiring and inspect the possibly faulty connection. I could easily see the connection (even through the 'coil of snakes' that was all the tucked-away wiring, it looked OK. I decided that since I was under there anyway, I would cut and splice the wire to make things neater. So as I pulled out the mess, I immediately saw an issue. The relay, especially the connection that goes straight to the battery was LOADED with corrosion - all green and gray looking. I immediately knew what my issue was.

I pulled the relay (after breaking loose the corrosion cement and initially thought that it was a 3-pin connection. Turns out, the battery terminal was so bad, that the pin had almost totally rotted away. After about 10 minutes of trying to clean and save the relay/harness, I made a trip to Summit Racing for a new harness and relay. Fast forward about an hour or so, and with 12 feet of exccess wiring laying on the floor, the new harness installed and the relay installed to the radiator support (a much better, more protected area), my lights were working flawlessly again. It was kind of cool, chilling in the garage - cup(s) of coffee at hand, with music playing from my phone and just tinkering with the car.

Anyhow, here's what the old relay/harness looed like - remember - this is AFTER being cleaned!

 

[CDX825]

Just proof that the crap they put on the roads here is highly corrosive.

 

[Nukeman7]

I will only use this waterproof style of relay for underhood applications (e.g., fog lights, horns) since they have a silicone gasket to preclude moisture intrusion to the terminal interface areas.

 

[Sequoiasoon]

I will only use this waterproof style of relay for underhood applications (e.g., fog lights, horns) since they have a silicone gasket to preclude moisture intrusion to the terminal interface areas.

View attachment 269311

I bought a set of like 10 of those either on eBay or Amazon that I use when doing lights. I will also put some di-electric/silicone grease on there where the female terminals are in case anything gets past the seals.

The ground connection may go straight to battery and if not gets the paint scrape/thread chase with a very light coat of Kopr-Shield but only at the grounds NOT like on multi wires close like the relay as it helps conduct while protecting.

Relays also get mounted with tabs down, screw hole up so anything can drain from inside relay on non sealed versions.

The wires themselves get waterproof connectors or heat shrink with the glue. My last fix was on daughters CRV, might have posted here, the ground wire from the lights part of harness was corroded inside the insulation and where it was crimped at a factory bolt under the battery area.

 

[eljefino]

GM put the airbag sensors for the GMT900 trucks in that area. As you'd expect, they fail all the time.

 

[willbur]

I bought a set of like 10 of those either on eBay or Amazon that I use when doing lights. I will also put some di-electric/silicone grease on there where the female terminals are in case anything gets past the seals.

The ground connection may go straight to battery and if not gets the paint scrape/thread chase with a very light coat of Kopr-Shield but only at the grounds NOT like on multi wires close like the relay as it helps conduct while protecting.

Relays also get mounted with tabs down, screw hole up so anything can drain from inside relay on non sealed versions.

The wires themselves get waterproof connectors or heat shrink with the glue. My last fix was on daughters CRV, might have posted here, the ground wire from the lights part of harness was corroded inside the insulation and where it was crimped at a factory bolt under the battery area.

That Kopr-Shield sure is expensive. I just use copper anti-seize-seems to work well (and cheap)

 

[Randol]

mechanical relays don't like vibration either, so keep that in mind.

 

[Sequoiasoon]

That Kopr-Shield sure is expensive. I just use copper anti-seize-seems to work well (and cheap)

I have had my jug for a long time. I got it because the electricians I was helping did it for many connections especially outdoors.

I also have copper anti-seize for other stuff. The Kopr-shield is a much thicker viscosity material and has a UL listing for electrical stuff. To me more correct material to help make a better connection.

Some people just use di-electric grease at the ground points also, basically something to protect water from getting in and corroding. I bought it long ago and still have a lot left, mine might be a 16oz container I think.

When I put a new battery in any of my vehicles I take the time and remove the ground cable and clean up the connections to fender etc and use it. My sons car the ground bolt connection rusted, cable got corroded. Lights flickered, radio would reset, horn randomly worked etc. Bolt snapped in fender attachment point. Had to drill and re-tap that and get new ground cable. All issues went away with same battery installed. How much was it the cable fault or the connection fault who knows but solid for multiple years now.

I do that as preventative just like using the copper anti-seize on brake rotor screws at first rotation/tire swap so I have no issues later when rotors need to be replaced.

 

[Sequoiasoon]

This was what I had to do to diagnose the fog lights not working. The wiring was a factory accessory kit that bolted to stock holes etc. The whole area where wire was got cleaned up, wire brushed and then when I was done covered with either Fluid Film or Blaster Surface shield. Battery and coolant reservoir totally block seeing it from above so had to be removed to work on it.

Corroded enough that with with solid power all the way, 2 LED Morimoto fogs wouldn't work from the resistance. Drove me nuts as both worked independently but together was too much. I had to cut back a couple inches of wire to get to clean copper.

 

[Don_M]

I will only use this waterproof style of relay for underhood applications (e.g., fog lights, horns) since they have a silicone gasket to preclude moisture intrusion to the terminal interface areas.

View attachment 269311

I was being cheap and in a hurry. The ones from Summit Racing weren't sealed like that, so I used liquid electrical tape and filled the wire-side of the pigtail with it. In the past, I had used gasket sealer from a tube and was able to inject the seal;er into the openings. This time, I also placed the relay tabs down, to prevent water, etc from getting into the physical relay and sitting inside there.