Hubs and superselect 4wd

[jcolvin]

Trying to troubleshoot friend's L400. Sometimes when braking she gets a "whirring" noise from the front end, almost like the hubs are partially disengaged or something. I jacked the front end up, and when you turn the left hand front wheel, the front driveshaft turns as well (in 2wd). Not too sure how the superselect 4wd works...does it disengage the hubs, or just open up the front diff?

[Green1]

The factory L400 hubs do not disengage, so the front driveshaft is always connected to them. The transfer case is the only place things disconnect.

[jessef]

You cannot disengage the front driveshaft / front axles. They are locked together.

The engaging/disengaging occurs at the transfercase = front driveshaft / front axles / hubs / wheels all move together.

Can you be more specific ?

Whirring noise isn't really something I would associate brakes/driveline with.

Have you checked the brakes ?

The slider pins (17mm bolts that connect the caliper to the bracket) are notorious for rusting inside and then not sliding = bad calipers = bad pads = bad rotors , etc...

If you're getting a jittering sound and/or feel it in the steering wheel or the brake pedal (floating up and down as you're braking), then look at the calipers/slider pins.

The likelyhood of anything going wrong in the front differential is next to none. It's a basic open diff which aside from gear oil maintains itself. Even if that's going, the sound you would hear is more like a deep metallic howl.

[jcolvin]

Well she has the flashing green lights on the selector panel for the front axle, I'm thinking perhaps the superselect is not disengaging properly. It doesn't sound like brakes, more like a clutch noise or something spinning. Hard to nail it down. Only seems to occur on deceleration.

[jessef]

Flashing lights are common on L400's coming over. If the 4wd isn't used for a long time, the contacts get old hence the constant flashing lights. I posted a while back how to fix it.

When you switch the tranfercase lever, it is a direct mechanical connection so it's either in 2H or one of the 4wd modes. There is no electronics.

If the sound is only on decelration than brakes are most likely the culprit.

[Green1]

what exactly do the front lights indicate?
On = 4wd
Off = 2wd
Flashing = .... It obviously knows that you're not in 4wd, but it's flashing... so is there something still not in position correctly? or why do they flash instead of turning on or off?

[jessef]

When you move the shifter, the lights will flash. Telling you it's been shifted. In reality, the mechanical connection has been made.

Shifting it back the lights will flash indicating a shift.

It's a simple mechanical linkage system. They just threw the lights in there as indicators just like the L300's. Same shiftin'

[Green1]

but WHAT do the lights indicate? they obviously know it's not in 4wd or they'd be on solid, so why do they flash instead of being off?

there's more to it than has been posted, I just don't know what.

[jessef]

Solid = engaged
flashing = connecting / disconnecting or engaging / disengaging

bottom solid / top off - 2wd
bottom solid / top flashing - 4H (awd) connecting
bottom solid / top solid - 4H connected

bottom solid / top solid / middle flashing (orange) - 4Llc (true p/t 4wd) connecting
bottom solid / top solid / middle solid - 4Llc connected

When you shift out of either of the 4wd modes, the same lights will flash as above indicating the shift.

The indicators are just indicators.

If they don't turn solid or are constantly flash, it's 99% that the contacts behind the cluster are loose/worn.

When you downshift from 4h to 2wd, the lights will flash and you'll hear/feel a subtle clunk as the driveline disengages. This is all mechanical. The lights are there to tell you what you can already see on the floor 4wd shifter.

When you shift the lever, it's in that 4wd mode right off the bat.

[Green1]

if the contacts couldn't tell I had changed then they'd be wrong, not flashing. the flashing must indicate SOMETHING or they wouldn't have bothered with it.

What you are telling me is that the contacts are working, because they know I shifted (otherwise they'd still be solid) but that the SAME sensor can't tell I shifted because it doesn't know to turn off the lights and flashes them instead.

There MUST be 2 sensors at work here. what is the second sensor attached to?

I have noticed that if I switch out of 4wd the lights will frequently flash until I let off the gas pedal, or in some cases until I cycle through reverse and back. It seems that there is something in there that can't fully disengage until the torque is released. I just don't know what it is.

[madmazda]

mine does the same thing once in a while but the only light that flashes is the center transfer case one I just wiggle the lever then it goes away....

[Mephisto]

I can only assume (as I don't have an l400) it is the same as the superselect pajeros, in which case the front differential itself has a vacuum pot that dissengages the diff. The flashing lights indicate that the actuator hasn't completed it's job yet, therefore, if you just switched into 4wd the vacuum to the actuator is turned off letting the actuator engage the diff but the actuator has not engaged yet and if you switched out of 4wd the actuator has not dissengaged yet. That is why green1 noticed the lights flash until load is released. The hubs are locked all the time but the diff itself engages and dissengages instead as well as the manual shifting of the transfercase from 2wd to 4wd.

[Mephisto]

When the center diff is flashing it is the viscous center diff in the transfer case waiting to lock or unlock as with the front diff if there is load the locking mechanism may have trouble engaging or dissengaging. Correct me if the L400 is different than the genII Pajeros.

[jessef]

L400 superselect tcase is the same as the Gen II Paj's.

[jcolvin]

Flashing lights are common on L400's coming over. If the 4wd isn't used for a long time, the contacts get old hence the constant flashing lights. I posted a while back how to fix it.

When you switch the tranfercase lever, it is a direct mechanical connection so it's either in 2H or one of the 4wd modes. There is no electronics.

If the sound is only on decelration than brakes are most likely the culprit.

No, this isn't quite correct. There's a mechanical connection in the transfer case but there's also a vacuum-operated disconnect on the front diff. When this is on the blink (could be many reasons from sensors to vacuum leaks) the lights flash. I'm wondering if it's only partially disconnecting. What I'm not sure about is what exactly the vacuum-operated thingy disconnects. Does it just open the diff (freewheel one of the front shafts?). or? anybody know? I'm guessing it might be that this isn't disconnecting fully hence the whirring noise on occasion. It certainly isn't brakes.