4x4only works if I manually lock the hubs

[matty21]

If the Hubs are set too auto and I switch the dash dial to 4hi I can hear the transfer case solenoid buzz then click in but only the back tires are are powered so it doesn't work. Yet if I manually turn the Hubs to lock, then it will engage and disengage like normal using the dash dial. Why would this be?
I don't want to have to drive around all the time with the hubs locked

[mazsecond]

Sound like your vacuum lines are clogged up. I had this same problem after I went through some pretty nasty mud. It gets all caked up around the vacuum line on the hub and on the actuator by the vacuum pump. Take some strong degreaser like Zep and soak the area where the lines connect to the hub and the actuator and rinse it off real good. If you can't you can go as far and take out your hubs and see how they look, they might need a good cleaning too.

[matty21]

ill try that,
thanks

[GregsSD]

Make sure your truck is moving when you switch from 2hi to 4hi, if your truck is not moving then the auto hubs usually wont be able to engage.

That is also why it usually doesnt work to shift into 4wd after you are already stuck if your hubs are set to "auto". The front wheels should be rolling to allow the hub to lock.


This is also one reason the hubs have a "lock" position, so that if you are stuck or the vacuum system is not working you can still manually lock the hubs and be on your way.

[matty21]

Originally Posted by GregsSD

Make sure your truck is moving when you switch from 2hi to 4hi, if your truck is not moving then the auto hubs usually wont be able to engage.

That is also why it usually doesnt work to shift into 4wd after you are already stuck if your hubs are set to "auto". The front wheels should be rolling to allow the hub to lock.


This is also one reason the hubs have a "lock" position, so that if you are stuck or the vacuum system is not working you can still manually lock the hubs and be on your way.

I know that , this is driving down the road. Besides the dash will tell you to pull ahead if it can't engage

[olypopper]

Not sure what your temps are but here in interior Alaska as soon as it got below freezing I had to manually lock for 4x4 to work. The auto option only works if I park in the garage all night, then no problems.

[matty21]

It's been around - 20C lately. That may be why, now it pops in and out with a cluck, unless the hubs are locked. Oh well it works when locked so I'm good .lol

[06BigRedPowerstroke]

Im trying to figure out this same issue with my 06 I can hook up a hand held vacuum pump to the line going to my hub and it locks in. I can put a gauge on my vacuum line coming into the Auto hub lock vacuum control solenoid and its pulling over 5. But the solenoid only allows it to suck for just a second before it stops and bleeds off so im thinking its the solenoid im going to try my buddies known good solenoid tomorrow and see if it works.

But i would recommend hooking a hand held vacuum pump up the hose going from the solenoid and to the front wheels lift the front wheels off the ground and start pumping while spinning the wheel and watch for the hub to lock when/if it does look at your gauge and make sure it doesn't drop off. If it locks and vacuum doesn't drop then from there down should be ok. May be the same issue as me I will let you know if the other Solenoid works.

[matty21]

Originally Posted by 06BigRedPowerstroke

Im trying to figure out this same issue with my 06 I can hook up a hand held vacuum pump to the line going to my hub and it locks in. I can put a gauge on my vacuum line coming into the Auto hub lock vacuum control solenoid and its pulling over 5. But the solenoid only allows it to suck for just a second before it stops and bleeds off so im thinking its the solenoid im going to try my buddies known good solenoid tomorrow and see if it works.

But i would recommend hooking a hand held vacuum pump up the hose going from the solenoid and to the front wheels lift the front wheels off the ground and start pumping while spinning the wheel and watch for the hub to lock when/if it does look at your gauge and make sure it doesn't drop off. If it locks and vacuum doesn't drop then from there down should be ok. May be the same issue as me I will let you know if the other Solenoid works.

Ya post if it helps, before I book an appointment

[grmreaper]

matty your not the only one. Had to lock hubs all winter long. Took it in. they charged me for a new hub + repack. Stated it had rust inside so they wouldnt warranty it. lasted 3 weeks before it wouldnt engage on its own again.