4WD system service required?!
4WD system service required?!
Evo has had a bad new year already, basically this: new tires put on >one tire just deflates overnight > put air in it for work > checked on it midday > tire flat again > spare placed on > complaint placed = free replacement and install 
> ride home = 4WD system required light comes on 
Wondering if anyone else has had this warning come on with their rides - I'm accounting the coldest weather we've had this year so far, as well as my misfortune of running my spare...My next day off won't be until the weekend, so fixing my problem will be an issue until then...
> ride home = 4WD system required light comes on Wondering if anyone else has had this warning come on with their rides - I'm accounting the coldest weather we've had this year so far, as well as my misfortune of running my spare...My next day off won't be until the weekend, so fixing my problem will be an issue until then...
The warning could be from driving around on tires of unequal diameter (from one being under-inflated). It could also be from the cold and your pump just died. If it clears itself after driving a few more times on four good tires, then forget it. If it doesn't, then be glad your pump is still under warranty.
I am going through the same issue as well, from what I read you could be low on fluid (AYC in the trunk) and the system just needs to be bled. my car is still under warranty so I decided to put my stock parts on and take it to the dealer. Hope others chime in
Last edited by Tribal; Jan 2, 2013 at 07:54 PM.
Had the same issue and all the fluids topped out, most likey the cause is due to the wheel speed sensor picking up unequal diameter during the wheels rotation like IOWA said. Make sure that the tires are balanced properly and are the correct diameter. When I had this issue and other similar issues like this with lients EVO X's I never got a single code, was wondering if you had gotten any codes when this happened to you?
Last edited by ILOVEBOV; Jan 2, 2013 at 10:36 PM.
it also sounds like it could be the same thing that Iowa said but related to the fact that the spare tire and the 4 (i guess 3) new tires are most likey different brands and different diameters...thus the awd system is sensing significantly (in its mind) different speeds between the 4 corners...
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What is it with you bringing up completely separate and, therefore, irrelevant issues in these threads? Are you purposefully trying to confuse people? In this case: tire balance cannot be in any way related to the OP's problem. Yes, under-inflation can cause a tire&wheel to be a tiny bit different in balance, but it is not going to cause any issues for any part of the S-AWC system.
I may have dreamed this and I'm not near my car to check, but I THINK the manual says something about that warning coming up when you are driving on the spare. Again I'm not positive but I seem to remember something about it ...
If you search around, you'll find various posts by people who had the AWD Service light when running on the spare. But you'll find an equal number of posts from people who got no codes. The spare's dimensions are a tad over 1% larger than the standard tires. Whether the spare deflects enough to keep the wheel speeds close enough to avoid the code would seem to be either random or so dependent on tire pressures that we end up with some people throwing codes and others not. In any event, the code should clear after a few miles on four matching tires, assuming no damage was done.
Of course, you'll definitely get a TPMS warning when running on the spare, but that's completely separate, obvious, and nothing to worry about.
Of course, you'll definitely get a TPMS warning when running on the spare, but that's completely separate, obvious, and nothing to worry about.
