AYC lights.... over lighting!

[jayjay99]

Got a problem at the mo, my first bar of the AYC comes on at random intervals when driving, I've tried to link it to anything but can't. It just comes on and turns off or may stay on for 30secs or more even when just going in a straight line. And when I go fairly hard round a roundabout I get squeeling so I believe something isn't working right. I don't have any red warning lights, the fluid is a perfect colour and level and the lights come on at startup as normal. I'm taking it to Eurospec this weekend for some other bits but am gonna have a look while it's there, just thought I'd get some ideas from you guys.

Cheers.

[bradc]

tyre pressures or tyre tread depth

[Nick Mann]

As Brad says, tyres are the first thing to check.

[jayjay99]

My tyres are cack, they are always looking low, mainly the front, but no matter how much I pump them up I can never seem to get them looking normal. Plus this started all of a sudden and never showed the lights before, I'll give it another go and see if I can change it. When a mate was looking at it in kwik-fit he was saying that it was like the car was too heavy for the walls of the tyres as he was putting way too much air in but just couldn't get them up?!?

[Nick Mann]

What's the load rating? I think VR4's need a minimum of high 80's, I always try and get load ratings in the 90's.

[jayjay99]

Ooh ok, didn't look at that before. Might be where I am going wrong, I'll have a look when I go out.

[bradc]

I run mine at 38psi front, 36psi rear and find it gives a nice hard ride and never causes me any issues with sidewall flex or AYC lights. I'm running Goodyear GSD3's with a load rating of 94 which translates to 670kg, which is heaps!

[Louis]

I run mine at 32 psi all round.
If you get a slow puncture or on tyre is at a lower pressure, it will show up on the ayc lights, also if you brake very hard they will come on. Whan you say squealing noise do you maen tyre squeal or is it a screeching noise from the rear diff??.

[jayjay99]

I run mine at 32 psi all round.
If you get a slow puncture or on tyre is at a lower pressure, it will show up on the ayc lights, also if you brake very hard they will come on. Whan you say squealing noise do you maen tyre squeal or is it a screeching noise from the rear diff??.


My tyres are a 92 rating, and the squeal is the tyres on the road. I think I might have figured it, I have different tyres at the mo as I'm about to buy some alloys and didn't wanna fork out for tyres. see if it goes after that.

[Eurospec]

My tyres are a 92 rating, and the squeal is the tyres on the road. I think I might have figured it, I have different tyres at the mo as I'm about to buy some alloys and didn't wanna fork out for tyres. see if it goes after that.

You mean different sizes between front to back?

If so, thats not great. You need to keep the rolling radius within a small percentage of each other front to rear. If its not then it will certainly stress the centre diff and probably upset the ayc too.

Hope that helps,

Cheers,

Ben.

[Kenneth]

You mean different sizes between front to back?

If so, thats not great. You need to keep the rolling radius within a small percentage of each other front to rear. If its not then it will certainly stress the centre diff and probably upset the ayc too.

Hope that helps,

Cheers,

Ben.

Different tyres front and back shouldn't make too much difference... A bit of diff noise perhaps but it shouldn't light the AYC up like that (a space saver on the front wont light up the AYC! ...all else being ok that is)

However... different tyres (ie wear level, brand or both) side to side is a big no no!

[d i c k i e s]

Always use the same brand. Some manufactures of tyres have certain readings for there tyres.

i have mine 34psi front and 32psi Back

[CANDEE]

You mean different sizes between front to back?

If so, thats not great. You need to keep the rolling radius within a small percentage of each other front to rear. If its not then it will certainly stress the centre diff and probably upset the ayc too.

Hope that helps,

Cheers,

Ben.

I ran mine with 205/55's on the front and 215/55's on the back for 18ish months and havent broken anything :)

[bradc]

the centre diff seems to be ok with tyre size differences front and rear, but the AYC doesn't like mis-matched tyres on the left and right sides, especially on the rear!

[jayjay99]

Yeah, the tyres are the same size, just different make. I wanna get some alloys and so don't wanna spend £180-£360 for a few months use.

[The Vee]

My tyres are cack, they are always looking low, mainly the front, but no matter how much I pump them up I can never seem to get them looking normal. Plus this started all of a sudden and never showed the lights before, I'll give it another go and see if I can change it. When a mate was looking at it in kwik-fit he was saying that it was like the car was too heavy for the walls of the tyres as he was putting way too much air in but just couldn't get them up?!?

Are the tyres the right width for the rims?

[ANTHONY]

will the AYC lights come on if you drive on the spacesaver

[Kenneth]

Yeah, the tyres are the same size, just different make. I wanna get some alloys and so don't wanna spend £180-£360 for a few months use.

The size is only approximate, you will find it differs between makes... You don't need much variation to change the circumference a fair bit either.

I suggest you put 2 tyres of the same make/size and wear on the back to stop over working your AYC.

[Nick Mann]

will the AYC lights come on if you drive on the spacesaver

Yes. I drove on the spacesaver once - only to the garage to get the puncture fixed. I wouldn't have liked to go much further - the AYC lights were like a disco party! And I wasn't driving hard with a spacesaver on the back either!

[bradc]

put the spacesaver on the front - if you've got brembos just face it the wrong way around, ie [ instead of ] so it clears them.

[Davezj]

I thought the AYC only worked on the rear axel and traction control worked on the front. I don't believe there are any hydrolic pipe running to the fron t of the car from the AYC pump at the rear.

But correct me if i am wrong.

[Nick Mann]

The AYC only powers the rear diff. BUT in order to work out what to do, it looks at the rotational speed of each wheel, plus the angle you are steering, plus throttle position etc.

So if any of your wheels is rotating at a slightly different speed, the AYC thinks the car is not travelling in the right direction for the steering wheel/throttle/etc application and compensates. This can lead to AYC bars when travelling in a straight line.

I'm afraid I can't comment on Tracion Control, but I was under the impression that this acts on the throttle body, therefore reducing power accross the board?

[bradc]

The AYC has sensors on all 4 wheels as Nick said, but what I've noticed is that it is more sensitive if the rear wheels are different. IE a space saver at the rear will definitely light up the ayc bars, but a space saver at the front doesn't.


The traction control does close the throttle body if it senses all the wheels are spinning. The car can't slow down just the front wheels or anything, but what it can do is individually brake each wheel if it thinks it needs to do so - thats what the ASC system does.

[Davezj]

good point about using a 4 wheel abs sensors to judge spin.