Automotive Electrical Relay Maintenance

electrical relays

My fairly new ARB air compressor suddenly stopped working. I’ve had it work pretty hard a couple of times and realize this thing has a fairly heavy current draw but figured the supplied components should be adequate.

Anyway, I was able to quickly trace the fault to the relay supplied with the ARB compressor kit. I opened it up and found that some moisture had made its way inside and corroded the contacts. Once you apply current, things fry up pretty good.

burned up contacts in relay

a burned up relay

If you’re unfamiliar with what a relay is/does – it’s quite simply an electromagnetic switch – apply a smaller current to the “coil” of the electromagnet, and it closes the contacts of the heavy current side. Use a relay and you can use low current switches inside your Jeep to control lockers, lights, winches, etc. instead of running heavy gauge wires everywhere.

I know better than to install without doing things properly and should have applied some dielectric grease – didn’t have any when I installed the compressor and then forgot about it until the relay took on water and cooked itself.

Here is my replacement Potter & Brumfield VF4-45F11 40A relay with some dielectric grease to seal out the moisture. Careful of what you use as a relay replacement – you want something capable of sustained high current draw. When I first installed the compressor, I had concerns about the Arb C042 relay being able to handle the constant current draw.

relay protection from water damage

Having background in electrical and electronics has me often taking shortcuts when doing electrical work on the Jeep. After-all, I pretty much know where the faults will happen and then fix them properly after. A bad habit to get into when I should be doing things properly at the time of install.

If you haven’t put some dielectric grease on the bottom of your relays, remember these things aren’t water proof and to do it asap – save yourself the headache of malfunctioning parts and the cost of new relays.

If you’re looking to upgrade your under hood relays to something waterproof, take a look over on Amazon – there is a low-cost Parts Express waterproof relay for less than $4.00. You can upgrade your compressor and light relays and save on some maintenance in the process!

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