AYC Issues....I think.....I hope.

[Likeashot]

Hey guys, well after we got the Leggie we had the red AYC light come on when travelling at speed, when the car was switched off for a bit it would go away but would come back on mainly when travelling at speed. So first thing I did was a ecu reset to make sure it wasn't just something funny going on, this fixed it for a couple of weeks then on the weekend we went to perth and all was good until we got on the freeway when a sound (and low freq vibration) started to come from the passenger side rear wheel area which I can only discribe as a low "wub wub wub wub wub wubbing" and when I say low I mean it was effecting my ears like a sub woofer, but no AYC light as yet, this sound came and went as it felt like high speed/low speed no pattern to it.
anyway the next day I went for a spirited drive using the AYC as much as possible and it worked fine although the wub wub wub came and went as well, after parking up for a couple of hours I went back to the inlaws to have the red AYC light come on and not go off this time, not wanting to cause any damage on the two hour trip home to bunno I pulled the AYC fuse from the dash and drove it home with no problems.

Now a couple of questions:

1). Should I pull the engine bay fuse as well?

2). As I like round numbers and was going to service the AYC/diff at the 110,000km mark along with the other service, is it ok to drive around until then (it's at 108,000kms ATM) with the fuse/s pulled?

3).Does this just sound like a servicing issue or something more?

BTW I haven't pulled a code as yet gotta find time to do so...

 

[TME_Steve]

Ayc light sounds like a pump on the way out not getting enough pressure intermittently, I would guess the noise is something else, check wheel bearings, and tyre wear and suspension joints etc etc. potentially the diff is gone but that should be a consistent noise....

 

[Likeashot]

The rear tyres are getting close to their wear marks, but as I said the vib/noise is very intermittent.
Would it be worth getting the adjustable pressure switch fitted?
Will it be ok (the AYC) to drive around with the fuse/s pulled until it' due for the service?

 

[naughtika]

check tire pressures on the rears.. make sure that the L & R have the same pressure, otherwise.. it can throw up that red ayc.. usually it goes by..

you drive off.. you hear the ayc pump turn on as if its trying to pressurize.. followed by the 3 ayc bars then you get the red ayc light.. and the ayc system would disable itself..

 

[Guest]

Pull both the fuses to be sure, driving it then won't do any more damage to the AYC. I also suspect the noise is coming from something else though and just a co-incidence so keep your mind open.

Then when you get your next service, flush out all the old AYC fluid from the hydraulic system and do a good top up and air bleed and see how it goes after that before making further decisions.

As you mentioned, adjustable pressure switches are one option but not an ideal solution. Your AYC pump will still be stuffed and not providing enough pressure, it's only tricking the light into going away and also stops the pump from continually running trying to build pressure to a level that it never reaches.

With the adjustable switch the idea is to set it lower than spec, so your system is always going to be below pressure. This will eventually get worse, cause your AYC clutch packs to slip and wear out and you may end up needing a whole new diff as well.

 

[Likeashot]

Thanks, yeah will pull both fuses and then do the full service and see what happens, I'll pull the fault code before then as well hopefully that'll shed a little light on the subject.

 

[TME_Steve]

Based on what i've been seeing of evo x sst boxes lately (that use wet clutches also) I wouldn't go anywhere near dropping the line pressure.... Different application but there's is a lot if torque going through a diff and slipping the clutches under a big load is exactly how a lot of sst boxes are failing. Change the pump if that's the problem....

 

[ECfiveA]

I had similar issues with the ayc light coming on intermittently with me. It turned out the TPS on the throttle body was giving false readings and needed to be replaced. It may not be the same issue that you're having, but if it is the TPS is the same on late model magnas so its readily available. It should be ok to drive, but be aware that the AYC is disabled whenever the warning light is on, so probably no need for the fuse to be pulled.

 

[Likeashot]

Based on what i've been seeing of evo x sst boxes lately (that use wet clutches also) I wouldn't go anywhere near dropping the line pressure.... Different application but there's is a lot if torque going through a diff and slipping the clutches under a big load is exactly how a lot of sst boxes are failing. Change the pump if that's the problem....

Yeah I'll see how it goes after the service.

 

[Mel-D]

check tire pressures on the rears.. make sure that the L & R have the same pressure, otherwise.. it can throw up that red ayc..

+1 this would be the first step as quite often this is the cause,and as you said the tyres are getting close to the wear marks so this could be it too, might be time to get new tyres

 

[Likeashot]

LOL I think I found the cause of the "wub wub wub wubing"

Will leave the AYC disconnected until I service it though, new rear tyres before then as well.

 

[Tophler]

I'm currently trying to find the error code which i'm assuming is there. I have followed all steps to get the code, used the paperclip method between pins 1 and 4 of the OBDII port but that only succeeded in getting the ayc, transmission and ABS light to flash constantly. There was no long or short flashes, just a constant flash with all 3 icons. Do you have any thoughts on how to get the error code?

 

[TME_Steve]

Error codes are flaky at best in these things, they seem almost not to be stored....

 

[Tophler]

so you're unable to check it out on a laptop either? i'm pretty sure the AYC pump is stuffed but even if its not, at least it will eliminate a possible cause and i'll know its good for another 100,000 or more

 

[TME_Steve]

If the code is active it will usually come up, but they dont seem to store very well....

 

[Tophler]

Thanks for your help everyone

 

[Likeashot]

Almost forgot about this thread, update time, the tyre was not the cause of the problem......the rear passengers side brake caliper was ceased holding the brake on hence causing a slight difference in wheel speed and the wub, wub, wubbing.
Got both the calipers kitted and new pads and all is well again, well almost all the red AYC light still comes on during long trips (not around town though) but will hopefully get sorted once I get the AYC serviced and the codes reset.

 

[pretzil]

Hey, when people talk about a noise from the AYC, could it be described as sounding like a radio aerial motor trying to put an aerial up (or a CD tray motor)?...
When I start driving, sometimes that sound comes from the rear of the car for about 15 seconds then stop for the rest of the drive, sometimes when this noise happens the AYC light will come on.

Once the light is off it stays off and AYC bars still light up normally, I'm assuming the AYC is on its way out...
Any chance it could just need a fluid change or top up? (wishful thinking, I know...)

Thanks.