How do you switch to 4 wheel drive in a Mitsubishi montero ls?

Answer 1

The top two lights are flashing because the front wheel drive detection switch is half way between open and closed... it isn't being properly pushed in or retracted when in 2wd (putting the vehicle in 4wd will likely make them light solid though, depending on the failure type).

What is going on here is you have either a broken vacuum line or a faulty Free-wheel clutch solenoid pack.

In order to engage/disengage the front wheels, vacuum is applied to either side of the actuator diaphragm to pull the the rod in the correct direction. If vacuum is lost, the actuator will not fully engage/disengage, tripping the switch inside the differential telling it that the system is between modes, and flashing the front wheel lights.

You will want to first go over all of your vacuum lines to make sure you have none rotted out or fallen off. If there was recent work done to the vehicle, you want to make sure there are no hoses crossed or pinched off, etc. Also watch where the lines come off the firewall as they sometimes get disconnected here. Depending on your intake manifold, you may have a rubber cap on the driver side rear corner pointing straight up... if this cap rots it will do the same thing.

If all of your lines appear OK, you will want to test and replace the free wheel clutch solenoid pack. The solenoid pack is located on the passenger side inner fender, just below the air filter housing... it is two side by side vacuum solenoids mounted to a bracket with 10mm bolts. Make a note of the vacuum hose arrangement (or photograph it) for proper reassembly order.

Most likely you will have one burnt out solenoid here so a resistance check will likely be your quick confirmation (open circuit would be bad of course... normal resistance is around 44ohms each). Other wise you can use your hand vacuum pump and check to make sure vacuum is allowed/disallowed based on voltage/ground application to each solenoid... if it is allowed to pass or not allowed to pass regardless of solenoid activation, again this would be a bad thing.

While it is possible the ecu is not telling the solenoid to fire, this is fairly unlikely... the solenoids are extremely common to fail however.

With regard to your ABS light coming on, you need to make this a secondary concern after the 4WD light issue. The reason for this is when the 4WD issue occurs, it is causing very small clutching of the front axle which will cause ABS anomalies. It is very common for the ABS light to come on as well when you have this 4WD problem. If the ABS light remains after the 4WD light problems are resolved, then we would want to look into that separately, though I do not think that will be the case here.

Check over your vacuum lines looking for any broken/disconnected/rotted hose/caps, and if all looks well there pull the freewheel solenoid pack for testing.... you will likely find it to be the cause as usual.

If you have any questions just let me know.

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