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Discussion Starter · #1 ·
Hi there, I hope someone might be able to help with my AYC dash light problem on my Evo 5.

The warning light came a few weeks ago and had the car checked. The garage could find nothing wrong, but were not too sure what would cause this problem. The fluid was replaced in the AYC Unit and they reckoned that would probaly fix it.

Since then the light has come on now and again, so much so that I have decided not to use it until someone can give me a straight answer. I have read on various discussion groups, that a faulty AYC Unit can destroy the rear diff, hence the reason for not using the car. The garage has checked the diff and can find no problem with it. All quiet at the back of the car thankfully.

My Evo 5 is part of the recall for the faulty AYC ECU's which I am waiting to receive. The local garage has suggested that I wait until that is replaced prior to further investigation into the warning light problem (I don't know if I will still be alive by the time that happens!!). I do not believe the replacement ECU will make any difference as this is not as I understand it, the reason for the recall. My car has never shown any signs of the fault for the actual reason behind the recall.

I have read in different threads on the forum, that it could possibly be the AYC fuse that has blown (attached to the |PLS| on the battery), or that there is a sensor at the back of the car attached to the AYC Unit itself which sends the signal to the ECU to confirm everything is OK. I atttempted to remove the fuse at the battery to check it without much success. It would appear to be completely stuck, or is there a special tool required to remove it? I have not yet tried to locate the rear sensor any info would be appreciated.

If anyone can be me any information I would be much obliged, or is my thinking that the problem is electrical completely wrong.


Discussion Starter · #2 ·
The product recall is actually to do with the AYC ECU having a fault or incorrect program causing the clutches in the AYC diff to operate incorrectly or at the wrong time. This apparently causes excessive wear in the clutches and wear means particles being stripped from the clutch plates. Obviously having particles floating about in your AYC system means even greater wear builds up. This is the reason why the AYC fluid is now changed so often to prevent build up of wear particles should the AYC ECU cause incorrect operation. It was originally quoted I believe that the AYC fluid was only supposed to be replaced every 45,000 miles and not every 4,500! As there is no official announcement from CCC/Ralliart to say what the exact problem is (I don't think they know anyway!) then what I have stated above is only my guess from information I have seen on other sites/forums. It does seem a logical idea though (well to me anyway but then again I'm no expert).

If you are worried then I suggest you disconnect the AYC system by removing the AYC fuselink from the battery terminal. I'm not sure how difficult it is too remove but others have managed it (ask Jon). This will not prevent the AYC ECU from working (so you may still get the light up) but it disables the mechanical side of the system (Accumulator, pump etc.) to prevent the clutches from working. If the clutches aren't engaging then they shouldn't wear.

I assume you took your car to a Mitsubishi/Ralliart dealer?
Their MUT-II servicing diagnostic tool should be able to read any fault codes stored in the ECU. If you AYC light is on then I guess a fault code should be stored. You can read most of the fault codes yourself by earthing Pin No.1 of the diagnostic connector with the ignition switch off. When the ignition switch is then turned on the AYC lamp should flash with the fault code. (YOU TRY THIS AT YOUR OWN RISK!).

The codes take the following form.

Pause between seperate codes of 3 seconds (i.e. lamp off)

Tens |EQU| Flash of 1.5 seconds with a gap between each flash of 0.5 seconds.

Units |EQU| Flash of 0.5 seconds with a gap between each flash of 0.5 seconds.

The Tens and Units are seperated by a gap of 2 seconds.

For example the Diagnosis Code No.24 is:
OFF 3 seconds
ON 1.5 seconds (|EQU|10)
OFF 0.5 seconds
ON 1.5 seconds (|EQU|20)
OFF 2 seconds
ON 0.5 seconds (|EQU|1)
OFF 0.5 seconds
ON 0.5 seconds (|EQU|2)
OFF 0.5 seconds
ON 0.5 seconds (|EQU|3)
OFF 0.5 seconds
ON 0.5 seconds (|EQU|4)
OFF 3 seconds (then repeating the code again or the next fault code.)

So that makes 24. (Incidently code 24 indicates an open/short circuit in the left-rear wheel speed sensor and will appear as a fault on the AYC lamp)

If there is no fault present and you try this test then the light will continue flashing on for 0.5 seconds then off for 0.5 seconds repeatedly.

N.B. To check the ABS system fault codes you need to remove the valve relay first.

You can clear all stored fault codes by disconnecting the battery for 10 seconds. It might be worth clearing the fault and then seeing if it comes back.

If you don't want to try it then take it back to your Mitsubishi/Ralliart approved dealer and get them to read the fault codes or reset it.

I will give it a try on my 6 at the weekend and see how easy it is.

Let me know if you get an error code and I will tell you what it is.

Discussion Starter · #3 ·
I agree with everything He Ho SIX says !!!

Remove the fusable link on the positive battery terminal marked with a little symbol of an axel.

disconnect the battery.....Undo the plastic fuse surround on the |PLS|ve terminal and undo the bolt holding the link in place. This will disable the AYC, but you will still see the AYC warning light blink at you as the main ECU tries to talk with it. Drive to a Mitsubishi dealer and then get them to replace the link and check the AYC using the MUT II computer. DO NOT GO TO ANYONE WHO HAS NOT GOT A MUT II !!

The AYC is VERY specialist and needs the correct diagnosis other wise you could be looking at a £3500 bill !!!

The fault may prove to be a badly fitted connector.

Good Luck !!


Discussion Starter · #4 ·
To remove the AYC 60Amp fuse, unclip the top cover. Then unclip the side covers. You can unbolt the whole thing from the battery terminal. Then use a 10mm spanner on the two nuts holding the fuse in.

Discussion Starter · #6 ·
Thanks for the info.

What scares me is that any of my local Mitsubishi dealers, look at you as if you've two heads when you contact them about problems like this. Not very impressive. I think they know how to use the MUT II as they used that to change the AYC fluid. At the time they didn't give me any details about it registering a fault.

I'll try and disconnect the fuse before I do anything else, then go and see them again and hopefully point them in the right direction.


Discussion Starter · #7 ·
Your local Mitsi dealer should have not have needed the MUT-II
to change the AYC fluid. The change procedure is a simple drop and replace.
You do need the MUT-II to bleed the hydraulic fluid in the diff system.
This fluid can be checked on a dipper in the boot ( RHS), the only way the AYC fluid can be checked is by removing the appropriate filler plug in the diff.
There's a possibility that they have replaced the hydraulic fluid but not the actual AYC fluid.
The gsr diff has 3 oils associated with it.The nomal diff oil that lubes the ring and pinion gears, the AYC fluid that lubes the clutch system and the hydraulic fluid system that actuates the torque transfer mechanism that provides steering assistance.They are all in separate compartments in the diff.
If in doubt get Ralliart at Dudley to change all your diff fluids, and/or check that your local guys have definitely changed the correct fluid.

If your car is part of the recall, it may be a good idea to remove the AYC fuse, the diff should then behave as a normal LSD and this should reduce wear,
but the AYC fluid still needs to be checked.

-Mr Mime
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