Wiring help switchpro to ARB compressor

2 years ago I installed a single (not dual) ARB compressor in one of the bed boxes. Wired from switch pro through arb harness with relay to compressor.

About three weeks ago the compressor stopped responding to power signal. Before that it worked flawlessly. I was able to air up all four tires effortlessly.

The other 7 accessories on my switch pro are working normally. The heavy hitters are a solenoid that powers my winch, 7xl light bar, rear Eaton locker and this arb compressor.

Compressor works fine when I jump it. (Pulled the unit and at the engine bay I ran new wires from battery to pos and neg on compressor)

Compressor relay is working fine, I went ahead and bought another arb relay just in case but no joy. (So technically there are two relays here the solid state switch pro and the arb relay)

compressor in line fuse is solid (see photo)

Wired into switch pro switch #8 gray wires (pair @ 35 amps). Gray wires are sending signal through wiring harness. (see photo)

My next step is to pull the entire harness but that’s going to be a bitch so before I do I was wondering if any wiring junkies could offer anymore trouble shooting advice.

Only other things I can think it might be:
-Bad pressure switch
-maybe I need to wire in the factory diode on red/yellow wire (see photo)

 

I know this probably won't help you in your current (no pun) situation, but did you install the Switchpro with a blue seal switch block? (I bought a kit which includes the two). If I were to install a compressor, I would just wire it to the blue seal so it would work when the truck is not running, and not go through the Switchpro. Sorry to not offer any help.

 

test lights won't show voltage. a volt meter is far better to verify the proper voltage is there.

if that's a solder-seal heat shrink, it looks like a cold solder joint-- the solder didn't flow all the way into the wire.

i would also check your ground.

what's the last picture?

 

Negative. Arb recommends to only use it when truck is on, also it helped cut down on all the extra switches. I hear ya tho

 

Thanks Bro, good luck with your issue. I'm sure you will get it figured out in no time.

 

MY only offer is try to crimp them bitches.

 

Any recommendations on a multimeter that can go up to 40amps? I think my south wire only goes up to 10.

yeah it’s a solder I seal I went ahead and redid it.

grounds are tight.

still no joy.

the last picture of the original post is part of the wiring harness that comes with the compressor. In that heat shrink is a diode that I never installed not sure if it’s relevant.

 

I am getting an audible click at the air compressor when I hit the power button

 

Probably a similar situation I had, where the wire was internally torched, either due to water intrusion and corrosion in the wire itself, or poor grounding. The wire probably has enough integrity for voltage to pass through but not current. I was pulling my hair out because I saw 12v and a good ground at my accessory, but the second I added load, I had nothing. Measure your voltage at the compressor wires with the compressor unplugged and switch pros on, I bet you it says 12v, but if you plug in the compressor, switch pros still on, I bet your voltage drops to 0. Could throw a current clamp on to confirm.

 

sorry for the late reply-- my dog got attacked by two loose dogs yesterday(nothing but a few scratches, but could've been a lot worse), and started making noise in the yard again tonight as i was trying to type up a response, so i had to jump up to check on him, and then ended up distracted trying to finish up the rest of my sunday night chores.

anyways...

try to wire nut the connections you solder-sealed. it still doesn't look very good. a properly soldered connection shouldn't have any visible copper. the solder should wick up into all the copper to make the joint. wire nutting the connection would make a temporary but strong connection, which would verify it's a connection issue, not a further wiring issue.

though i definitely prefer heat seal crimps to solder seals, as just about anyone can make a good strong mechanical connection by smashing, but solder requires proper cleanliness, flux to overcome surface corrosion, and appropriate temperatures of all the copper to get the solder to wick as needed. i would even go so far as to say that solder seals are likely not a great connection for that size of larger of wire-- it takes far too much heat to solder large gauge wires like that, and the heat shrink outer will melt first.

as far as volt meters and 40A, you're confusing electrical measurements. like horsepower and torque. the old saying "horsepower is how fast you hit the wall, torque is how far you drag the wall with you". voltage is like horsepower, and current(40A) is like torque. they work together, and in some ways are indiscernible from each other, but are also two distinct measurements.

the volt meter you've got now will work plenty fine, and will actually work better than an amp meter-- you'll need to be on the '20v' setting at about the 10:00 position. what we need to look for in this case is voltage drop. the air compressor is calling for more amperage than 'something' can supply to it. the key is to figure out what/where that 'something' is. this will be evident with the volt meter-- it will read battery voltage on all connections when the switch is on, but the compressor is disconnected, but then drop to under 10v, likely closer to 2-5v once the compressor is connected. being that the relay is now clicking, measuring at the compressor(end of the line), many automotive relay's will get triggered at 5-7v.



so that's the preliminary 'why it don't work' and what tools/settings need to be used to troubleshoot. next is there to help, but a large part is me chopping up your previous post so i can work through what you've already tried, and the questions and test points to check after that.

simple enough.

this jeep forum post should be the basic diagram you followed for your connections, correct? they call out using s-tech output #1, you're using #8, but same switching and battery/power/fuse connections/locations.
https://wranglertjforum.com/threads/arb-single-compressor-wiring-simplified.41461/

the switch pro really shouldn't be an issue here. to eliminate it, we could try using a different output, but i expect the same result, so it's not really critical to try. it's not carrying any of the major load, the ARB 40A relay is doing that, which means as long as you can hear the ARB relay clicking on, which you indicate later on, the switch pro is going to be good.

going back to the diagram, you're connecting directly to the compressor on the "red/white and black/white" denoted in the above diagram?

at this point, we've really got two questionable parts-- there's the ARB relay, which has been diagnosed to be working, and there's also the pressure switch.

at this point, i would recommend taking a piece of wire, unplugging the red and and blue from it as indicated in that diagram, and jump across them(with the switch pro output turned on). if the compressor runs, it means the pressure switch is bad. if it doesn't, more troubleshooting is needed. specifically, i'm going to be looking for more pictures of your ground connections, the path from the compressor to the battery. your ground bar looks good.

 

I appreciate this advice, I will try this troubleshoot this weekend. Any recommendations on a good current clamp for this application?

 

Haha damn soundman I always appreciate your advice and seeing you advise others. Fucking Goat.

First, glad your dogos are okay. I keep a bamboo switch in my yard for this very reason. No worries on the delay.

yeah as I was installing these solder seal connectors I noticed they looked off. Probably buying a $15 kit on Amazon wasn’t the smartest idea. 10/4 on the wire nut I will try that approach. lol you’ve obviously been around the block because thats why the solder isn’t fully melted because the heat started melting the plastic. I’ll stick to the crimp shrink connections.

thank you for explaining that my multimeter will work and verifying the correct setting.

10/4 my next step will be to check voltage drop. I will test at the end of the loom where the compressor is connected, for troubleshooting I put t connectors on the short black and red wires going to the compressor to have a place to put the multimeter probes. Verifying at least 5-7v.

In regards to wiring set up, the diagram you referenced is how my compressor is set up with the exception of #1 slot vs #8 slot.

I can confirm I hear the ARB relay clicking, glad I tried without the engine on otherwise I wouldn’t have heard it.

For devils advocate I will swap to another SP slot for the next round of troubleshooting.

As the diagram indicates red white is connecting to the relay and black white is connecting to ground, not the battery but to my bus bar in the engine bay.
To jump start the compressor I did however connect the compressor straight to battery.

Yes confirmed ARB relay is working and I do have a new spare just in case.

I did actually troubleshoot the pressure switch at the very beginning of this entire ordeal. As you mentioned I connected the red and blue wires going to the pressure switch in order to bypass it but when I clicked the button on the switch pro there was no response from the compressor.

Again to reiterate the ground going from the compressor is not going directly to my battery it is instead going to the bus bar. It’s roughly a 13ft continuous run of 12GA wire.

 

I always use fluke products but they’re pricey

 

lol I’d say most of us here that spend money on our trucks are use to pricey. Which fluke clamp would you recommend? I googled them but there’s quite a few options

 

I can’t remember the model name of the one I have, but you’re right there are a ton, just look at them and get the one with the most features you’re comfortable spending on this. If you don’t frequent electrical work often, maybe just get a “cheap” one. It’ll service your purposes just fine, might not be super accurate but will atleast tell you if there is or isn’t current flowing through those wires.

 

10/4 thanks for the help.

 

Honestly if you already have a multimeter, do the test I suggested with measuring voltage with no load attached, then measure with load attached, circuit on both times, and see if your voltage drops to 0. If it does you don’t even need a current meter to know that your not passing any current through the wire

 

Good thought, haha I’m always looking for tool recommendations is all. 10/4 I’ll report back with my findings. I’m hoping I’m not going to have to pull the loom as I bundle all my runs together so it gets annoying pretty quickly.

 

just be sure to use a heat shrink crimp tool-- the jaws are smooth and flat, so they don't cut through the heat shrink less than other crimpers.

i use this one every day, with the second link being my backup/garage pair. i like the grip of the first one a little better.

$32 KF CPTEC 5PCS Ratchet Wire Crimping Tool Kit with Quick-Change Jaws for Heat Shrink, Insulated & Non-Insulated Connectors, Ferrules, Open Barrel, OT & UT Terminals – with Storage Case

https://www.amazon.com/KF-CPTEC-Crimping-Tool-Set/dp/B0B68V9NHL

$20 Plustool Crimping Tool for Heat Shrink Connectors AWG22-10, Ratcheting Wire Terminal Crimper - Crimping Pliers - Electrical Crimping Tool

https://www.amazon.com/Plustoool-Crimping-Connectors-Ratcheting-Crimpers/dp/B0BGXDD5Z8/

so the switch-part of the relay is working because it's clicking, but there's a potential here that the power input to it, or the power output is going to be bad--either in the relay itself, or the relay holder.

you should be able to remove the relay, and probe the contacts-- one will be constantly powered as the input. i've also seen bad fuse holders cause similar issues. the best way to test this would be to use your test light as a load, and measure the voltage with the test light lit. if there's a poor connection, the voltage displayed will be different from your battery voltage by more than 0.1v.

it's also a good test to do with the relay installed, and enabled, to check the output wire going to the compressor, but with the test light being used instead. this would eliminate the fuse, fuse holder, relay, and relay holder portion of the installation.

you can also test the pressure switch partly. if the compressor hasn't built pressure, you can use the ohm setting on the meter and read a direct short(0.00 ohms, or very close) across the two contacts of the pressure switch. when the compressor reaches pressure, it will open those contacts. anything less than 135psi will keep the contacts closed to complete the circuit.

so while jump-starting the compressor verified that the compressor is good, it also means that there's a lot going on between the compressor and the controlling relay up front.

i'm suspicious of your wire size. a simple test here would be to use a set of jumper cables to connect from the ARB relay output and your ground strip to the compressor located in the back. if it works, the problem is in the wiring between the front to the back, which would then need to be replaced.

ARB's specification sheet calls for a max load of 32A.
https://www.arb.com.au/assets/air-lockers/6-07.pdf

when setting up wiring, the general rule is to keep the anticipated load less than 80% the capacity of the wire. each wire size has a specific resistance per foot. resistance translates to heat, and larger wire has both less resistance, as well as a easier time dissipating that heat.

12 gauge wire over 13-ish feet for a 32A draw is far too small.

this blue sea systems chart is a nice reference for power wiring runs.
this page has an expandable version of the chart that's far easier to read
https://www.bluesea.com/support/art...oosing_the_Correct_Wire_Size_for_a_DC_Circuit


the compressor should be set up to the '40A' wire size category. given the longer distance, and the power draw(can't forget about the start-up power draw, that's typically larger than running power draw), i would feel far safer with the 6 gauge than the 8 gauge wire.

the main issue here is that DC voltage operates differently than AC voltage. in household AC voltage, the power 'jiggles', or reverses 60 times every second. so the power's not really 'flowing', it's just moving each little part, which moves the next little part, etc. it means that the wires resistance doesn't build up over time as much, which makes it less susceptible to distance problems. AC is more like moving water around in your mouth from one cheek to the other.

DC is very different, in that power flows only one direction, and at a constant rate. it means that the length/resistance of the wire slowly builds, which negatively effects both the voltage and current available at the other end. DC is more where the typical 'straw' analogy comes from. the longer/thinner the straw, the harder it is to suck or blow a fluid through it.

also, you really don't need to be running the ground all the way back to the ground bar/battery. you can just as easily attach to the frame in the back of the truck, and then add(never replace) an additional ground strap from the factory chassis ground to the battery.

typically, it's preferred to go to the frame-- essentially the frame is one really large 'wire', so connecting to it eliminates the 'double straw' problem-- where a device is trying to 'suck' power up through a tiny power wire, but also get 'push out' used power through another tiny straw. that double restriction can create additional issues, so in many cases where people want to run dedicated grounds back to the battery, they over-size by at least one gauge, sometimes two, above the power wire size to ensure the 'used' power is returned to the battery as effortlessly as possible.

after going through this, i'm really quite sure it's going to be the under-sized wiring causing the issues, more than any of the connections.

ironically, they're the only meters i've never had good luck with. i've burned through 2 different models, both with different unreliable problems.

a major distinction here is that you're going to need to look at one that can do DC current if you intend to use it in vehicle projects. that's going to be very different from normal. the starting unit is going to be the 365, with the 325 being the next in line, and then the price breaks $500 for the 374, 375, 376 that are capable of dc current monitoring.

i had a 902 that just decided to stop reading AC voltage while working in a 480v factory--not the time for a volt meter to tell me that something has '0 volts' on it! i put it on my time-out bench for 4 years, and now my dad's used it consistently for a while with zero issues. also had a 375 for a while that randomly decided it didn't like reading current. the only fluke that's not been a 'fluke' is an ebay-bought 't+ pro' volt/continuity meter. if i had only that meter, i'd whole-heartedly trust fluke meters. it's been all but submerged in a lake and still works perfect despite it's worn looks, and that was after whoever used it for an unknown time and sold it on ebay for $70.

i use an older variation of the FLIR CM85-2, which is part of that $500 mark.
https://www.flir.com/products/cm85-2/?vertical=condition monitoring&segment=solutions
overall, i've been extremely happy with it, it does more than i could ever want, from different readings, as well as bluetooth recording of the output, and it reads consistently (accuracy might be debatable on certain functions, but i don't need accurate as long as it's consistent--i'm comparing reading 1 vs. reading 2, 3, 4.... 10 with the same tool. not recording, reporting, or documenting to third parties).

FLIR's cheapest dc current offering is going to be the VT8-600 at $140, though historically, the open current test loops haven't always offered the most consistent readings. i know it was an issue with early fluke designs like it, i can't say either way if the bugs have been worked out.
https://www.flir.com/products/vt8-s...rtical=condition+monitoring&segment=solutions

 

From what you did I’d suspect that SP ckt could have failed, why not swap the compressor with another similarly rated load and see if that works.....just because it's all integrated doesn't mean it can't fail.

Especially if you jumped power to the ARB......and ASSUMING you applied the power to the ARB's circuit not just it's connections.