Twin Arb Compressor Mount Behind The Rear Seat For 2017+ Superdutys

[Huck Norris]

There’s a relay inside of the ARB compressor that can fail in a closed state as well.

Did you dive into this and figure out what happened? Could help another member if they run into this same issue.

Well, I finally had time to dedicate an afternoon to this problem and it turned out that it took about 4 minutes to identify the problem.

Tested the purple wire at the compressor and upfitter was good. Zero when off and 12v+ when on. Which meant the issue was within the compressor.

Realized that the compressor was shooting air out both over pressure valves and neither were ever shutting off.

Ordered two new relays and new pressure switch. Installed one relay, one compressor worked as it should, other didn’t shut off. Installed second relay, both compressors operate correctly again. Did not change the pressure switch.

The only thing I can’t figure now is how both relays got nuked. I’ve also had the two big inline fuses under the truck both go out on my previously. Something in my install seems to be causing a power problem.

 

[BroncoHooves]

Well, I finally had time to dedicate an afternoon to this problem and it turned out that it took about 4 minutes to identify the problem.

Tested the purple wire at the compressor and upfitter was good. Zero when off and 12v+ when on. Which meant the issue was within the compressor.

Realized that the compressor was shooting air out both over pressure valves and neither were ever shutting off.

Ordered two new relays and new pressure switch. Installed one relay, one compressor worked as it should, other didn’t shut off. Installed second relay, both compressors operate correctly again. Did not change the pressure switch.

The only thing I can’t figure now is how both relays got nuked. I’ve also had the two big inline fuses under the truck both go out on my previously. Something in my install seems to be causing a power problem.

Maybe the relays were failing and blew the fuses under the truck? Glad you got it figured out now. Do you have any pics of the disassembly or the new relays?

 

[Huck Norris]

Maybe the relays were failing and blew the fuses under the truck? Glad you got it figured out now. Do you have any pics of the disassembly or the new relays?

I didn't take any photos, but it's pretty straight forward. Just remove the bolts on the bottom, pull off the heat shield and they are plugged in right on the back. Two standard looking 4 blade relays. 12v/40a. PN: ARB-180905SP which I got from Summit Racing: https://www.summitracing.com/parts/ARB-180905SP. So nice to have air back!