# Accuair Switchspeed Wiring Issue



## DarkSideGTI (Aug 11, 2001)

I've been driving my car for years with only one of my compressors working. I finally decided to see why my other compressor was not working. 

This is my setup.









I am wired just like this diagram.









I used a vampire tap and figured that was the issue. Today I removed it and sure enough it was not making contact on the spade that cuts through the wire. So I wired it differently, this time the yellow wire comes into a butt connector and the other side of the butt connector has two wires coming out, one going to each relay. That is all I changed and now for some reason neither compressor is kicking on. When I turn the ignition on, I can hear a click coming from the Switchspeed ECU but nothing else happens. I have double checked my wiring and grounds and everything looks fine. I also always work on my cars electrical system with the battery unplugged. Not sure what is wrong at this point.


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## DarkSideGTI (Aug 11, 2001)

I let the car run for a few minutes to see if maybe it was an issue with the battery not charging or something. after a few minutes the 3 numbers on the controller started flashing. According to the manual this means there is some sort of wiring issue. But as you can see above everything appears to be hooked up correctly.

The compressor should still kick on even though my lines from the VU-4 to the bags are not plugged in right? I had to unhook them in order to gain access to my wiring.


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## MechEngg (Jan 13, 2009)

Having the plumbing for the VU4 has no ill effects on the wiring or the ECU so you should be good there.

Wiring looks good, i would double check your relays first just to make sure they are both functional, then test your compressors by directly hooking up the leads to the battery. 

If your relays are good and your compressors work then its time to test your pressure switch. Are you just using a standard pressure switch and not the one provided by Accuair i'm assuming? If so then put 12V to one terminal and test the other terminal voltage with the pressure in the tank higher than the cutoff. There should be no voltage on the second terminal. Then release air from the tank and at the low pressure setpoint the switch should allow 12V to be read on the second terminal. 

If your pressure switch is working then triple check your grounds :thumbup::thumbup::thumbup:


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## [email protected] (Aug 22, 2006)

MechEngg said:


> Wiring looks good, i would double check your relays first just to make sure they are both functional, then test your compressors by directly hooking up the leads to the battery.


This is a winner right here!

Speaking from personal experience, those cube relays don't have the greatest longevity. I much prefer the stinger relay or the Tyco 75A relay. :thumbup::thumbup:


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## DarkSideGTI (Aug 11, 2001)

I'm leaning towards some kind of wiring issue. The one compressor was working fine yesterday as was the relay. I think I'm going to redo my grounds tomorrow.

Are 85 and 86 reversible? Looking at that picture above from my install thread the yellow wires are opposite of the wiring diagram that I followed today.

this diagram also shows it wired the opposite way.
http://bagriders.com/modlab/tech/dualc_wd.pdf


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## MechEngg (Jan 13, 2009)

DarkSideGTI said:


> I'm leaning towards some kind of wiring issue. The one compressor was working fine yesterday as was the relay. I think I'm going to redo my grounds tomorrow.
> 
> Are 85 and 86 reversible? Looking at that picture above from my install thread the yellow wires are opposite of the wiring diagram that I followed today.
> 
> ...


Yes 85 and 86 does not matter the polarity, as long as there is 12V across them


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## fasttt600 (Apr 12, 2007)

DarkSideGTI said:


> I'm leaning towards some kind of wiring issue. The one compressor was working fine yesterday as was the relay. I think I'm going to redo my grounds tomorrow.
> 
> Are 85 and 86 reversible? Looking at that picture above from my install thread the yellow wires are opposite of the wiring diagram that I followed today.
> 
> ...


switch both wires on 87. if the compressor that wasn't working switched to the one that is now working and vise versa, then you know you have a ground issue. If neither work at that point. then you know you have a bad cube relay of bad fuse.


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## DarkSideGTI (Aug 11, 2001)

fasttt600 said:


> switch both wires on 87. if the compressor that wasn't working switched to the one that is now working and vise versa, then you know you have a ground issue. If neither work at that point. then you know you have a bad cube relay of bad fuse.


I did try that yesterday and neither still worked. I also checked the fuses and they are all in tact. The Switchspeed controller still works and activates the valves.


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## MechEngg (Jan 13, 2009)

Dumb dumb thought but what is the pressure in your tank currently? Just want to make sure that it isn't above the cutoff pressure of the pressure switch.

Again test the relays, then the compressors directly, then the pressure switch directly. Since you are running a mechanical pressure switch and not the accuair transducer those are the only possible things that it can be


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## DarkSideGTI (Aug 11, 2001)

MechEngg said:


> Dumb dumb thought but what is the pressure in your tank currently? Just want to make sure that it isn't above the cutoff pressure of the pressure switch.
> 
> Again test the relays, then the compressors directly, then the pressure switch directly. Since you are running a mechanical pressure switch and not the accuair transducer those are the only possible things that it can be


The tank is completely empty. I had to remove the air lines going to it yesterday. It is currently hooked back up though and the outlet is going to the VU-4 manifold.

I am using the pressure switch included in the Accuair kit.


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## MechEngg (Jan 13, 2009)

DarkSideGTI said:


> The tank is completely empty. I had to remove the air lines going to it yesterday. It is currently hooked back up though and the outlet is going to the VU-4 manifold.
> 
> I am using the pressure switch included in the Accuair kit.


Ah okay thats what your wiring showed in the first picture but your second diagram depicted the mechanical pressure switch so i thought you may have rewired it at some point.


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## DarkSideGTI (Aug 11, 2001)

yeah the pressure switch line in that diagram is the yellow line from the Switchspeed ECU.


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## proshot (Apr 22, 2004)

Are you getting 12v on the yellow wire with key on?


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## DarkSideGTI (Aug 11, 2001)

proshot said:


> Are you getting 12v on the yellow wire with key on?


I'm going to try to test that tonight. It is difficult as I have to lift up my box to get to the wiring and some of the grounds are too tight to lift it up much.


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## DarkSideGTI (Aug 11, 2001)

I tested the relays and I was seeing 11.6V to the compressors and so it pretty much confirmed my suspicion of a bad ground. I re-did the grounds from the ECU and relays so it went 4 into 1 then grounded that with a larger gauge wire. But it ended up being the compressor grounds which strangely I hadn't touched. O well, I'm just glad to have both compressors working now. :beer:


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