ML Triton - 4WD stopped working

[P0m81]

Hi guys. I have checked the forums but can't find anything quite like my problem.

I have a 2008 ML manual. Last time I went on the beach I started having the 4WD light flash when in 4WD or sometimes not lit at all. I also noticed occasionally it would flash after starting the car on the road then go away. Now it just has no 4WD light and seems to be on 2H whether I select 4H or 4L.

I took it in for a service and mentioned this to the mechanic, they diagnosed it as 4WD solenoids (like many of the posts on here). The mechanic is a friend of a friend and suggested I could save a bit of money if I buy the solenoids from eBay and do it myself. I've since replaced the solenoids and hasn't helped. I put 12v on both of the old solenoids and they both click so I don't think they actually did have anything wrong. I've checked both solenoid power connectors and they both have 12v when in 2WD and both have 0v when in 4WD. I've taken the vacuum hoses off the actuator and one of them has vacuum when in 2H and when I switch to 4H, the other one has vacuum instead.

I've watched the actuator while someone puts in/out of 4WD and I can see the actuator moves back and forth. I did notice the actuator bracket was a little bent so the actuator wasn't square with the diff casing so I bent it back to be square again but still no difference.

From what I've read, if the actuator is moving, I would have thought it should be working. I've taken it for a test drive on a dirt road near my house and it feels the same in 2H/4H/4L so I don't think it is a case of the 4WD detector switch just not working (and after I replaced the solenoids and started the car, I did get the 4WD light flash on for a second then off again so I know the dash light still works!).

I also thought 4L should put me in low range even if the front diff isn't engaging but that isn't happening either!

I know a few of you have a bit of experience with this. Any advice would be much appreciated!

[grox]

All I got is did you peel the dust cover back and check the connection between actuator and rod that connects Ito engage 4wd . If it's bent in there you will loose a few mm of travel. I've broken a few and we used to just undo that actuator connection and tie with wire to get 2wd going home on road . So you could undo same connection and push the rod towards the wheel to see if that engages. I've got my09 ml so has super select but should be the same ie default is 4wd vacuum when you start engine pulls it into 2wd . If your have lost any distance through a bend etc maybe it's not far enough to engage . Also if any hose has come off it sucks in crap real quick worst is sand and stuffs solonoids I put in Chinese toy bike filters to stop it. Someone with an older ml should be able to provide other electrical / relay answers if it's different from the tritons with super select.

[P0m81]

Thanks grox, I'll try that. I did pull the dust cover back and and saw the actuator going in and out but didn't let see what you are talking about so probably need to peel it back further.

[msrlo]

if the fork is broken is broken on the actuator it wont engage

[P0m81]

Went for a 30 minute drive today (on the road) and decided to put it in 4H afterwards for shits and giggles and 4WD light came on! Switched between 2H and 4H many times and light responded instantly. 4L, light would go off though.

So then I drove to the dirt road near my house again and tried driving in 4H and the light would flicker sometimes while driving in 4H. Got It actually driving in both 4H and 4L with light on solid for a bit though. Then the light wouldn't go out in 2H until I shifted in and out a few times and drove in circle a couple of times.

So it's engaging but very intermittent. Sound like the actuator still?

[als1200]

I had a pajero that used to play up.
i wish i could remember the exact fault but i removed a detent switch on the top of the gearbox/transfer case cleaned it and all was fine. I think (smarter people can correct me) but i think low range was activated by one of the detent switches as it activated a solinoid in the box.
i was told use it more so problems dont occur

[variflex]

I had this issue a while ago and simply replaced the rubber freewheel hub cap, she is found ontop of a tube that runs up the firewall, unfortunately I don't have a photo, PM me your mobile number and I'll go take a photo of the part I'm talking about,

[P0m81]

I had a pajero that used to play up.
i wish i could remember the exact fault but i removed a detent switch on the top of the gearbox/transfer case cleaned it and all was fine. I think (smarter people can correct me) but i think low range was activated by one of the detent switches as it activated a solinoid in the box.
i was told use it more so problems dont occur

Hi als1200, I've got the service manual and can see where the switches are on top of gearbox you are talking about. How do you access them though? Can you reach them from inside the cabin if you remove the gearsticks/rubber boots etc?

[als1200]

No i got to them from underside. Bent a 22mm spanner (from memory) once cracked it was very easy to undo by hand.

[dwhylan]

From the Manual below, your vacuum hoses may need replacing.

A vacuum type freewheel clutch has been adopted for 4WD vehicles, and it has the following features.
•This device is composed of main shaft, clutch sleeve, clutch gear, shift rod, and shift fork, etc.
•The freewheel clutch assembly is electrically and automatically controlled utilizing an ON/OFF signal from the 4WD detection switch which is located in the transfer.
•The solenoid valves are either activated or deactivated to change the passage of vacuum to the actuator according to the ON/OFF signal. Operated by the actuator, via the shift rod and shift fork, the clutch sleeve slides to either 2WD or 4WD position to select the drive train mode.
•A vacuum tank is incorporated to provide a better freewheel clutch operation.