Before reading this I suggest people read the Mitsubishi Super Select System article first to get a full overview of the systems operation.
Mitsubishi super select systems are one of the finest four wheel drive systems known, but there have been a few issues and they are often very easily overcome.
Mitsubishi Super Select systems employ an electronic centre differential to bias the power of the four wheel drive system, this is a torque biasing system which biases the torque between the front and rear axles as required, it is normally biased 67% to the rear axle and 33% to the front axle, but can vary considerably and bias all the torque to one or other of the axles as required by grip levels or driving requirements. As the system is electronically controlled it also has the ability of a locking torque convertor on automatic models to provide a solid connection between the engine and wheels and this engages automatically as and when it is required.
Due to these two parameters the mode selector which selects 2H, 4H, 4H locked centre diff, and 4L are also electronically selected and this works in conjunction with the other electronic systems to engage the drive mode you select, basically it will pick the optimum time to select 4H when shifting on the fly, and prevent the system trying to change modes when its not safe to do so, so basically its a failsafe to prevent transmission damage. In the wilds of nowhere you can get a vehicle stuck if the system doesn't engage immediately, but if it allowed to transmission engage it could trash the transmission; you can recover a stuck vehicle; but a vehicle with a trashed transmission is going nowhere.
One problem is called the flashing light syndrome, this is when you try to move on the fly between 2H and 4H or 4H back to 2H and all four green lights flash; or all the green lights extinguish and the centre differential orange light flashes, or when all four green lights flash rapidly.
This is usually down to nothing more than sticky switches on the mode selector and they come as a set, changing them is easy but they cost around £120 a set, so the simple answer is to lubricate them. This is simply done as all you do is remove the multiplugs and clean with electronic cleaner and plug them back in and coat with a good spray of Waxoyl as this protects them and it is electrically inert.
Spray the switches with a hosepipe as vehicles regularly used offroad can accumulate a lot of dirt around the switches so cleaning them regularly with a hosepipe is beneficial; avoid using a jetwash on them as the pressure can be excessive and damage them. Get a good lubricating ot maintenance spray and absolutely lather the switches with the spray as this will penetrate then and remove any muck and properly lubricate them, go inside the vehicle and move the mode selector through all positions and fit the straw to your can and fire plenty of spray down the mode selector through the plastic sleeve which moves with it, this will ensure each switch in each position is fully lubricated and will cure most problems. Do this regularly, at least twice a year and this will keep them lubricated.
Exercising the system is essential, don't use two wheel drive all year and suddenly be surprised that four wheel drive won't enagage when you suddenly find snow on the ground, to stop the system sticking you need to exercise it every week or fortnight to move the switches and keep them free and operating.
Select a piece of grass verge or similar, or a piece of off road terrain which is at least twice the length of your vehicle and park your vehicle on it, with the transmission in D (auto's) or 1st (manual) all you do is move from 2H to 4H and let it engage, drive forwards one vehicle length and reverse back, then switch back from 2H to 4H several times.
With 4H selected you now engage N or P positions (auto) or neutral (manual) and move the mode selector from the 4H position to the 4H centre locked diff position, drive forwards one car length and reverse, then disengage it and move back to 4H, do this several times to keep the switches moving.
To select 4L you select 4H locked centre diff and engage N or P or neutral and move the mode selector from 4H locked centre diff position into 4L, drive forwards one car length and reverse, disengage and repeat several times.
To lock the rear diff you move the mode selector into 4L and let it engage, move the rocker switch to engage the rear axle diff lock and let it engage, if it doesn't engage firts time select a gear and creep forwards a few inches and it will engage, disengage the rear axle diff lock and engage and disengage several times to ensure it works.
This takes a few minutes to do and is easily done to exercise the 4WD system, this keeps the switches operational and prevents any problems from occuring, do this every week or fortnight and when the snow comes exercising your system will ensure it slips between modes as smoothly as silk.