Confirming the 4wd is working

Sorry in advance if this is a stupid question.

I am trying to confirm that the 4wd is working on my new jimny. And also to get it clear in my mind how the mechanics of it all work.

I took it on a wet field and the back wheels were still spinning like mad but could't tell if the fronts were doing any thing (my 1st 4wd)

When I select 4wd the front prop does lock up yet with one front wheel lifted off the floor it spins freely, I have read that it shouldn't spin?

The local motor factors said that i need to have both front wheels in the air and they should spin togeather? I suspected the front diff might not be working but he also said that it would be banging its nuts off if it was knackered.

Can anyone help out.

Thanks

In 2WD, only the rear axle drives.
In 4WD three things happen:

1) the front hubs lock with a "CLICK", they are air operated, and will only work with the ignition on, and possibly the engine running (there is a small reservoir though under the wing)

2) the front propshaft locks to the rear one. This forces the front and rear axles to turn together, and is a GOOD THING on mud, as the drive is split 50%, making the wheels less likely to spin.
This is a VERY BAD THING on tarmac, as the front and rear axles need to go at different speeds around corners, so the tyres scrub, (if you are lucky) and the CV joints break.

3) 4WD low activates an epicyclic reduction gear as well, to reduce the wheel speed, and provide more torque at the wheels, for steep slopes, and deep mud.

To test,

Engine running, engage 4WD, the hubs should click. Handbrake on, jack up one front wheel, and try to turn it by hand. It should only turn a few degrees each way. If it goes round and round, most likely the hubs didn't lock.

Engine running, engage 2WD, the hubs should click again. Handbrake on, jack up one front wheel, and try to turn it by hand. It should go round and round.



Don't use 4WD on tarmac, and be careful in the wet, a Jimny will spin round and round very easily.

Enjoy

Thanks for the information, with the engine running and one wheel of the ground the wheels go round and round, so thats why I thought that the diff might be knackered.

Next question how do you check the hub operation

I removed the black centre of the wheel (6or8bolts) which looks like it locks the wheel and drive shaft together. After a bit of probing it seems to jump into place so guessing the operation is working, I will try and find the vacum hoses and work back over.

If the vacuum system is leaking, the 4WD light flashes to tell you the hubs couldn't lock. (Not didn't, it can't tell, it only measures the vacuum when the hubs are activated)

There is a big section on checking the control system in the manual, check the usual suspects for a download.

If the light is steady, then likely there is a blocked pipe, or someone swapped the pipes over :huh:

The light is a steady green, so i'll check the pipes for blockages.

I just started thinking the worst, and cursing the bloke I bought it off. Hopefully it will be something simple

See the guide

www.bigjimny.com/images/documents/Check_the_vacuum_system.pdf


Martin