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Discussion Starter · #1 ·
Hello all, I have recently purchased a 2004 Pathfinder Armada LE and the original owner had the Air Shocks removed and replaced with stock shocks because he was tired of replacing them. The rear suspension was a rusted mess so I just installed all new control arms, springs, etc and continued to use the aftermarket basic shocks in the back. It appears when pulling a trailer the rear sags too much so I want to go back to the air leveling shocks. I have access to the 2004 service manual and have verified the fuses 12, 14, 19 in cabin as well as 9 and 29 in the engine compartment. I noticed that the compressor image in the manual shows the relay being part of the compressor, but this is not true (or at least not visible) - parts.nissanusa.com indicates all models 2004-2009 have the same compressor part number so then when I looked at relays for 2004 it shows 1 relay (25237-EA000) behind the battery for the air suspension. I was able to swap relays and still not working. Next I used a volt meter and confirmed continuity where there should be, but for voltage on pin 2 for the compressor harness I see only 7.5 volts (IGNITION OFF) and 8.5 volts (IGNITION ON) when there should be 12 Volts on that line. Looking at the Suspension Control Unit buried behind the drivers side rear panel in the 3rd row seat I was able to test inbound harness voltage to this unit, and pins 6 & 7 are a little hot at ~14Volts when I should haver 12 volts.

That being said with only 8.5Volts out of the suspension control unit (28581-7S600) I am assuming it is the issue and found a USED ebay one for $50 as the revised part 28581-7S602. While I wait to receive this unit I wanted to reach out to see if anyone else experienced this low voltage issue to the compressor from the suspension control unit before and what their fix was. Thanks in advance.
 

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I have never messed with the air suspension and know very little about electrical matters. I do know that they make "helper" airbags that you ca install inside of springs for the p urpose you describe. I believe you p ump them up via external air to whatever pressure you desire. I think they are goodyear or firestone as far as brand, there's aYoutube video of a guy installing them on his standard springs. The reason he did it was the same reason you did, towing. I don't think they're that expensive.
 

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I've got and 04 with air shocks. They seem to work. Are you missing the shocks and compressor too?
 

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Discussion Starter · #4 ·
Thanks for the replies. Current update is that I ordered a used suspension control unit, new compressor, and new height sensor. Just got them all installed today and verified the old compressor did not work when applying voltage manually to it... new compressor works with manual voltage applied but not in the armada. Checked the voltage from the replacement suspension control unit and again it reads 7.5Volts instead of 12 volts as stated in the manual. At this point I'm not sure if the CONSULT software used by the dealership has options to disable the system? I know there is a diagnostic mode, but I don't have the CONSULT software to pull a reading..... Still researching what the cause may be.
 

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I’m pretty sure I was able to reset the height sensor with my Autel scanner from work. Might have to try something like that. I assume all your fuses and relays are in place?
 

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Discussion Starter · #6 ·
The wiring diagram in the manual shows fuses for FUSE BLOCK 12 - 10A, 29 - 10A, and "g" - 30A. All appear to be good. What I have not been able to verify is the relay behind the battery. There are 2 of the same relays behind the battery:
(site does not allow link from parts.nissanusa.com
Part 25237U

One of these is for the RSU-air suspension, the other is labeled as T/F - ETS MOTOR (XNJ), not quite sure what that relay is for, but since they are the same part I swapped them and still did not work. Hard to believe that both relays would be bad.....

I'm looking to find scan software to see if I can pull any diagnostics from the suspension. Since I still have 3rd party shocks (not the air shocks) I have been trying to disconnect and force the height sensor to a low state, but not sure if there is a wait period for detection since it does not seem to force the compressor on.

still investigating...
 

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One of those relays is your 4x4 and the other is for the auto-leveling suspension. If your 4WD works, then that relay is fine.
 

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Discussion Starter · #8 ·
I just went through the multimeter voltage and continuity validation again. With the used replacement Suspension Control Unit 28581 7S602 I still get 7.5 volts on the compressor harness....should be 12 volts. I can validate all fuses good, I tested the relay this time and it does click when applying voltage, and I can validate the height sensor is working 0-5V on pin 2 back to SCU when turned.

On the harness to the Suspension Control Unit I get pins 6,7, and 15 at 12V and pin 16 has continuity. The manual says if that checks out then replace the Suspension control unit. So I am going to give it one more try and bought another used ebay 28581 7S602 for $59. Fingers crossed!!!!

I was curious if anyone knows whether the SCU can be programmed with a height adjustment that would cause it to never operate (i.e. purposefully disable it). It seems that the CK SUSP also does it's 2 second self check and turns on with ignition but then goes OFF and never turns on even when I set the height sensor to indicate low suspension.

Thanks!
 

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It seems that the CK SUSP also does it's 2 second self check and turns on with ignition but then goes OFF and never turns on even when I set the height sensor to indicate low suspension.
I don't know about reprogramming, but the CK SUSP light in the Armada is garbage. It only lights up in a handful a scenarios, and total system failure is not one, neither is the compressor shutting off permanently since it stayed on too long.

Basically, when I first bought it, the system was completely not operational. The relay was fine, but the compression, SCU, and height sensor were all bad and needing replacement. I also had a rupture in the driver's side bag and both lines from the compressor were replaced. Once all those were replaced (most of it by the dealer under our extended warranty), I found out while moving across the country with a heavy trailer that there was still a leak in the passenger side bag. It was a very slow leak, but it was enough that the compressor would stay on for 5+ minutes, after which, it would shut off completely unless my wife pulled a fuse and put it back in while I was driving or we turned off the vehicle and turned it back on.

Throughout all of this, the CK SUSP light would only come on for the two seconds when first starting the vehicle and then stayed off. See this post for more details on what the system is able to detect, without bothering to notify the driver with the light.
 

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Discussion Starter · #10 ·
I don't know about reprogramming, but the CK SUSP light in the Armada is garbage. It only lights up in a handful a scenarios, and total system failure is not one, neither is the compressor shutting off permanently since it stayed on too long.

Basically, when I first bought it, the system was completely not operational. The relay was fine, but the compression, SCU, and height sensor were all bad and needing replacement. I also had a rupture in the driver's side bag and both lines from the compressor were replaced. Once all those were replaced (most of it by the dealer under our extended warranty), I found out while moving across the country with a heavy trailer that there was still a leak in the passenger side bag. It was a very slow leak, but it was enough that the compressor would stay on for 5+ minutes, after which, it would shut off completely unless my wife pulled a fuse and put it back in while I was driving or we turned off the vehicle and turned it back on.

Throughout all of this, the CK SUSP light would only come on for the two seconds when first starting the vehicle and then stayed off. See this post for more details on what the system is able to detect, without bothering to notify the driver with the light.
Thanks for the reply and link...you have quite an extensive writeup! :)

I'm still waiting for my used (3rd) replacement SCU, once I have that and if it tests the same, I found a resource to connect a snap-on diagnostics tool to pull the air levelizer codes (if any).... more updates to come.
 

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Discussion Starter · #11 ·
Thanks for the reply and link bassmadrigal...you have quite an extensive writeup! :)

I'm still waiting for my used (3rd) replacement SCU, once I have that and if it tests the same, I found a resource to connect a snap-on diagnostics tool to pull the air levelizer codes (if any).... more updates to come.
 

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Discussion Starter · #12 ·
3rd SCU came in... same issue.... so I think my last resort is to get the consult/some other programmer that can read the air suspension codes and diagnostics....I can only assume there is a setting saved in the computer that is disabling the height sensor readings...
 

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Discussion Starter · #13 ·
Current update - my brother has access to the ETHOS Edge snap-on Diagnostic Scanner and hooked it up. It did not appear this unit supported the detection of the air suspension system no matter what year/model we selected (Armada, Titan, QX56), so we were unable to pull codes or reset the height trim. However we did use a powerprobe to validate the circuit is good. We can confirm the height sensor is sending voltage to the Suspension Control Unit and that pin 1 on the SCU is not generating any voltage to the relay to engage the compressor. Using the power probe we can directly apply 12V on pin 1 harness and verify the circuit is working and relay/compressor work as expected. It is highly unlikely after 3 used SCU replacement units they are all bad, so we can only conclude the configuration saved for the air suspension is essentially disabling the functionality. My last resort is to go to the dealership to get their CONSULT or whatever diagnostic tool to reset the trim and other settings as this will be cheaper than purchasing a CONSULT or Similar diagnostic tool that supports suspension diagnostics.
:(
 

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Current update - my brother has access to the ETHOS Edge snap-on Diagnostic Scanner and hooked it up. It did not appear this unit supported the detection of the air suspension system no matter what year/model we selected (Armada, Titan, QX56), so we were unable to pull codes or reset the height trim. However we did use a powerprobe to validate the circuit is good. We can confirm the height sensor is sending voltage to the Suspension Control Unit and that pin 1 on the SCU is not generating any voltage to the relay to engage the compressor. Using the power probe we can directly apply 12V on pin 1 harness and verify the circuit is working and relay/compressor work as expected. It is highly unlikely after 3 used SCU replacement units they are all bad, so we can only conclude the configuration saved for the air suspension is essentially disabling the functionality. My last resort is to go to the dealership to get their CONSULT or whatever diagnostic tool to reset the trim and other settings as this will be cheaper than purchasing a CONSULT or Similar diagnostic tool that supports suspension diagnostics.
:(
Thx for all the info. I have the same problem.... Did you find a solution for the low voltage coming to the compressor? I'm getting 8.6.
 

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Discussion Starter · #15 ·
Thx for all the info. I have the same problem.... Did you find a solution for the low voltage coming to the compressor? I'm getting 8.6.
Hi mirkas I have been meaning to update this. I was able to resolve my issue. It WAS software related. I was able to obtain a CONSULT III tool (check out http://www.obdii365.com/wholesale/nissan-consult-3-iii-professional-diagnostic-tool.html). I made a video of the process, but did not edit/upload yet. Once I do I post the link. Essentially the previous owner had the suspension disabled by having the mechanic set the auto-level sensor on the rear suspension in the maximum position then reset the auto-level calibration in the tool. This basically made the suspension EVER turn on and there was no way for me to resolve without the CONSULT tool to reset the saved value. Once I was on a level surface and reset the auto-level calibration in the tool it is now working again and has been great with towing the travel trailer we have.

Unfortunately I was unable to find a method to reset the air-levelizer suspension without the CONSULT tool (although it was mentioned there was an autel scantool that could do this - however I could not confirm it would work from any of the available documentation and was not willing to pay $500+ to hope it would work.) Hopefully this is helpful and again I'll post the video when I get the time. Good Luck
 

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Hi mirkas I have been meaning to update this. I was able to resolve my issue. It WAS software related. I was able to obtain a CONSULT III tool (check out http://www.obdii365.com/wholesale/nissan-consult-3-iii-professional-diagnostic-tool.html). I made a video of the process, but did not edit/upload yet. Once I do I post the link. Essentially the previous owner had the suspension disabled by having the mechanic set the auto-level sensor on the rear suspension in the maximum position then reset the auto-level calibration in the tool. This basically made the suspension EVER turn on and there was no way for me to resolve without the CONSULT tool to reset the saved value. Once I was on a level surface and reset the auto-level calibration in the tool it is now working again and has been great with towing the travel trailer we have.

Unfortunately I was unable to find a method to reset the air-levelizer suspension without the CONSULT tool (although it was mentioned there was an autel scantool that could do this - however I could not confirm it would work from any of the available documentation and was not willing to pay $500+ to hope it would work.) Hopefully this is helpful and again I'll post the video when I get the time. Good Luck
Thx so much JeffKraus for fast respond. I'm going to purchse the consult 3. The video would help. I just bought my 2004 armada and trying to figure out why the leveling system doesn't work. When I check the voltage it was low 8.55V but i didn't check anything else so far. Just found your post and was thinking to start there. I don't know if you have time for this or I better create new post... Does the car need to be on level surface or driveway uphill is ok for the auto level to kick on? Do you think that bad relay could lower the voltage? thank you
 

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We have a 14 Platinum 4wd and ours doesn't work either. 79k.

General question, just under normal driving conditions and if the system is working correctly, should the compressor kick on for a short time every time the vehicle is started?
Or, does it come on only to 1) level the rear during a tow 2) compensate for an air leak.

I have yet to swap the relays or run leads to the compressor itself. The other day I started it, crawled under and didn't hear anything from the compressor, hence my question above.

The rear ride height is about 1.5" lower than the front, so it's not too bad. I taped it to a bit under 35". I think it should be closer to 37?
 

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Discussion Starter · #18 ·
For me, the compressor does not come on each time I start the vehicle, but definitely when I hook up the tow trailer and that pushes the suspension down. Once the suspension levels out I dont hear it kick back on. When removing the trailer the shocks are over filled and the system releases the excess pressure back to level. My guess is you may have a air leak
 

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Thanks Jeff. First thing is to get power to the compressor and see if it actually comes on. Will report back.
 

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From my understanding, the system is designed to rely on a little bit of air in the shocks, so if the compressor is working, but there's a slight leak, it will likely kick on every time you start the vehicle to add the air back that leaked out. It is designed to be airtight, so barring leaks, once it has air in the system, it should never need to adjust the air level unless the weight in the back of the vehicle changes enough to cause the system to adjust the height.

Also, there is typically a 30 second waiting period for the timer, so when you start the vehicle, it won't typically kick in the compressor for about 30 seconds after it realizes it needs the adjustment.
 
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