ARB Compressor wiring mystery - help needed please.

[JPAloha]

I’m hoping to find someone who’s encountered the same issue or has better knowledge of electrical than I do to troubleshoot.

I’ve transplanted the ARB single compressor that was in my WK2 into my wife’s 4xE Rubicon, it makes sense that we’re more likely to take the JLU off-road than the Grand Cherokee (though we’ve taken that off-road a few times).

My power and ground wires were already extended from the WK2 install so I ran them through the passenger side wiring grommet nipple. That was a pain the butt and not something I’d look forward to doing again, lol.

Initially I was going to keep using the ARB switch but in troubleshooting my issue I’ve utilized Aux 3 and connected it to the solid red wire that would have gone to the switch and comes from, I believe, the pressure switch.
On the relay I’m getting power to the red cable from the battery, the ground wire is working for my multimeter to get readings so also good. I can jump the red wire to the red and white that goes to the compressor and the compressor runs (also proving my ground wire to the battery is good).
When I turn on Aux 3 I can hear a relay in the dash click and it is supplying power to the red lead.

However the relay in the ARB wiring does not click and so doesn’t bridge the red cables. I know the obvious answer is a bad relay but I’ve tried 5 that all bench test as good with a multimeter for resistance.

The red trigger wire goes to the pressure switch and the blue pressure switch wire comes back to the relay block , perhaps acting as the trigger.

My mind now goes to the pressure switch having gone bad since removing from the WK2 a few weeks ago and installing in the 4xE yesterday/ today. I’m willing and happy to be proven wrong though.

After messing around with this all day I’m tired, grumpy and my back hurts, help a guy out would ya? ?

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[falcon241073]

Show pics. I don’t have a red wire going to my arb compressor other than the 12v wires that connect to the battery. The wire for the switch is blue (may have been purple. I’ll try to find a pic if I have one)on my arb. But then I didn’t use any or the arb harness since I’m not running air lockers. I ran the power and grounds where the battery and a body ground. Ran the blue wire to an aux switch. I have yet to have an issue.

 

[JPAloha]

Show pics. I don’t have a red wire going to my arb compressor other than the 12v wires that connect to the battery. The wire for the switch is blue (may have been purple. I’ll try to find a pic if I have one)on my arb. But then I didn’t use any or the arb harness since I’m not running air lockers. I ran the power and grounds where the battery and a body ground. Ran the blue wire to an aux switch. I have yet to have an issue.

My dual has a purple trigger wire, this is for a single.

 

[falcon241073]

My dual has a purple trigger wire, this is for a single.

Ahhh. I’m missed the single. And didn’t realize arb used different colors for their trigger wires. Sorry I can’t help. Been a long time since I installed a single.

 

[Suffolklou]

It sounds like your wiring setup is correct. You could check the pressure switch by measuring voltage on the dark blue wire with aux 3 on.

You should also check that aux 3 is giving you voltage. You can set it up different ways in the radio menus so it may not be optimal. I use Aux 4 for my twin compressor though.

Considering aux 3, my relays are in my fuse box under the hood and I dint hear them click when I mash aux buttons, although I don't have a 4xE so your could be a whole different setup.

Last thought, there should be a solid black wire with the relay that also gets grounded.

 

[Suffolklou]

I do not think you need to use the ARB relay, just the single, in the case of my twin it was purple, switch wire to the AUX switches.

The twin has a relay in between the compressors, the single needs the relay.

 

[Jazzicon]

The trigger switch connects directly to the AUX switch wiring.

The twin has a relay in between the compressors, the single needs the relay.

Ahhhh, okay. Disregard anything I have said. In my defense, it is 5 AM.

 

[JPAloha]

It sounds like your wiring setup is correct. You could check the pressure switch by measuring voltage on the dark blue wire with aux 3 on.

You should also check that aux 3 is giving you voltage. You can set it up different ways in the radio menus so it may not be optimal. I use Aux 4 for my twin compressor though.

Considering aux 3, my relays are in my fuse box under the hood and I dint hear them click when I mash aux buttons, although I don't have a 4xE so your could be a whole different setup.

Last thought, there should be a solid black wire with the relay that also gets grounded.

I appreciate your reply. The ground wire to the relay block runs with the main ground to the battery, I’ve been using that point on the relay block as my ground when using the multimeter so believe that to be good as I don’t think I would get any readings if it weren’t.
Aux 3 is set to be on with ignition and as a locked switch, the option being as a press and release, I will double check its giving voltage tonight.
I’m not sure I checked the blue wire to the relay block with everything on so will do that tonight. It is starting to sound more like the pressure switch has picked its moment to go bad, I may bridge the pressure switch wires if the other tests show the Aux switch is giving power but the blue wire does not.

The only other thing I considered was the Aux switch rating, on my 2 door I only had Aux 1 remaining which is rated 40A, Aux 3 & 4 are rated 20A but as it’s job is simply to trigger the relay I thought it would be fine. Thanks for confirming as you’re using Aux 4.

 

[GATORB8]

To help with troubleshooting, here's the wiring diagram (includes the solenoid portion for lockers)

I'm trying to follow the posts above:

Power circuit:
12 V+ to 40 amp to Red to Relay to Red-White to Motor to Black/White - Checked okay by jumping relay.

Switch Circuit:
Aux 4 to Red to Pressure Switch to Dk Blue to Relay to Black to Ground. - Unproven Pressure switch and Relay.

Relay Circuit:
Switched: Red to Red White - Confirmed not switching, but may be trigger
Trigger: Red to Pressure Switch to Dk Blue to Black to ground - Unproven

So, need to confirm:
1. Aux 4 power to red at pressure switch
2. Pressure switch operation (need to confirm system is not at pressure before jumping)
3. Relay operation by supplying 12V+ to Dk Blue

 

[JPAloha]

So tonight I confirmed the pressure switch is the issue.

I turned everything on, ignition and Aux 3, bridged the pressure switch wires and the compressor turned on. I also bridged the hot wire on the relay with the blue trigger wire and the compressor came on.

A new pressure switch is now on order. Of course, nobody in Canada seems to have one so I have to pay 150% of the part cost for shipping, yay!

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