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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8621
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Code 35 and 33 center lock light keeps flashing and stays on

Customer Question

code 35 and 33 center lock light keeps flashing and stays on 2wd
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.


These codes are both strongly indicative of a bad free wheel clutch solenoid pack (located on the frame rail below the air filter box).

Specifically, the code 33 is indicating a problem with the transfer switch operation, and the 35 is indicating a problem with the free wheel engage switch. This is not to say that both are "bad", simply that they are not in agreement and so the computer doesn't know whom to believe with regard to the drive mode selected.

What happens on 90% of these vehicles when you have these codes is the free wheel clutch solenoid I mentioned before will fail; when this happens the free wheel engage switch on the front axle will not full turn on/off and will not agree with the transfer lever position. It is worth noting that this can also happen if you have a vacuum supply issue to the solenoid, so if this condition formed right after any engine work was performed, verifying the vacuum hoses would be a good idea in case something got left off or connected wrong.

Otherwise the free wheel solenoid pack can be tested with a multi meter, hand vacuum pump, and a spare battery. Each of the two solenoids should read around 35 ohms resistance (+/- 15% for age is OK). If either shows dead short or open circuit, the solenoid pack is bad.

The operation of each of the valves is tested by hooking up a hand vacuum pump and then applying/removing voltage to the solenoid. If either solenoid passes vacuum regardless of voltage (even a slow trickle) or holds vacuum regardless of voltage, the solenoid pack is bad.

Diagnosis this way should only take about 10 minutes once the vacuum lines are all verified first of course; if found bad, replacement takes literally a few minutes. The free wheel solenoid pack for a 2003 full size Montero would be part number MR430381, lists for $145 from any Mitsubishi dealership. It is not available aftermarket, but can be bought from discount dealers like Mentor Mitsubishi online for a discount (about $110 instead).

Expert:  Doug replied 1 year ago.

I got your other message, if the site is giving any issues there we can continue here if needed instead.

Customer: replied 1 year ago.
how and where the mechanic have to check for the vacuum leak on the 2003 mitsubishi montero ? because the center lock light is still blinking . thanks
Expert:  Doug replied 1 year ago.


The vacuum leak check it pretty standard protocol any mechanic should be familiar with. Your entire intake manifold, injector sealing area, PCV system and all vacuum hoses are your leak points. Any where that is under vacuum is at risk of a vacuum leak. They can check for a leak by spraying brake cleaner or propane around the intake tract while the engine runs... if there is a leak it will draw the added "gas" in and affect the idle.

If no leaks are found and the solenoid pack is already replaced and ruled out, then we would have to consider physical interaction of the front axle next, followed by actual switch readings last.

To check the physical operation I would be putting a hand vacuum pump on the front axle actuator and manually putting it into 4wd and 2wd and seeing if the light goes out. If it does, then you know you missed a vacuum issue somewhere since direct application makes it work. If the actuator won't move fully into one range or the other, then you would suspect a physical failure (be it actuator/diaphragm or the internal fork in the axle etc, rare though). If the actuator fully engages/disengages but the light still comes back on even after unhooking the battery and the front axle is properly engaged for the given selection, then and only then would you expect a switch issue.

Customer: replied 1 year ago.
my mechanic will check for the vacuum leak on Tuesday . i will let you know the outcome .
Expert:  Doug replied 1 year ago.

Sounds good, good luck!

Customer: replied 1 year ago.
good morningg,
sorry for the delay. my mechanic changed the freewheel clutch solenoid and checked for any vacuum leaks. there was no vacuum leaks. However, the center light differential is still blinking . do you think that i should change the five switches on the differential? i already bought them. i took the truck to 3 mechanic shops none of them can find the problem. please, help me with a shop on long island ny . thanks
Expert:  Doug replied 1 year ago.


I would not change the five transfer switches without diagnosing them first, reading their position on the scan tool to see if one is not responding.

Being that you are seeing front axle related faults are directly related to the freewheel system, really there is very very low probability of the five switches being at fault... the 2wd/4wd switch on the transfer lever maybe, but that would be it and it is very unlikely (unless the truck goes under water regularly).

At this point I would be putting a hand vacuum pump directly on the actuator and manually trying to engage 2WD. If you can't move the actuator then there is either a problem with the diaphragm or the fork itself in the axle, or extremely unlikely but the detection switch on the axle (They rarely fail though); if you can and the light can be cleared then something was overlooked with the vacuum/freewheel solenoids most likely, as the system is capable of disengaging mechanically, but the vacuum control is not operating properly. We could speculate on the ecu/wiring, but given that you are seeing trouble codes for this behavior it makes it nearly impossible to be ecu related.