4wd light flashing on dash

if you follow the air pipes up the radius arm they go to rubber pipes, you can carefully prize off the rubber pipe and suck on each pipe (one at a time) with your mouth, they should 'click'
you probs wont be able to blow down hard enough to reverse them, i found a foot pump with worked. when my vacuume system packed in i used this technique for a while. people would laugh as i used to get under the car at each offroading event and do the same before driving home at the end of the day to manualy blow / suck the hubs in and out !!

just to add if the car hasnt been in 4wd for a long time they may just have seized and need a bit working to free them up

how could you pump them on thay work on vacuum for a few seconds to go on and off

Blowing will make them work the opposite way round.

They are actually blown over by the pressure of the atmosphere acting on the side where there is no vacuum (the vacuum takes the pressure away from one side).

I would be careful about blowing them with a tyre pump or airline though, you may blow a seal out somewhere if you use more than a few psi.


How the system actually works (and what went wrong with mine)

There are 2 pipes to each hub. Each pipe goes to one side of the diaphragm inside the hub. One moves it out, the other moves it in. The hub has a bias, so once it has moved it clicks into place and stays in/out.

The two pipes run to 2 solenoid valves.
Each valve has 3 spigots.
1=atmosphere (has a little filter cap on it)
2=vacuum (both valves join together, and connect to the manifold tapping, as well as a small tank under the wing. There is a non return valve between the tank and the manifold too.)
3= the line to the hub (each valve controls one side, the "in" has a vacuum switch attached that works the 4wd light.)

When switched off, ports 1&3 join, and port 2 is sealed, so a vacuum builds up, and both sides of the hub are open to the air.

When you select 4wd

The lever moves the gears in the transfer case, and activates the 4wd switch. This signals the controller that 4wd has been selected.
The controller activates the "in" valve, joining ports 2&3, so vacuum reaches one side of the hub.
Atmospheric air goes through the other valve- ports 1&3 to push the hub over with a nice "click"
The vacuum built up in the line to the hub now switches the vacuum switch and the 4wd light comes on. (if no vacuum builds up within 5 seconds due to a leak, the light flashes, the hubs likely didn't move as there was no vacuum)
The "in" valve is released after a few seconds.

Select 2wd

The lever moves the gears in the transfer case, and the 4wd switch turns off.

The "out" valve is activated- ports 2&3 join, and vacuum is applied to the diaphragm, air enters through the "in" valve and pushes the hub over with a "clack"
The "out" valve is released after about 10 seconds. There is no monitoring switch for "out"


In my case, the "out" valve leaked all the time between ports 2&3 so there was never any vacuum built up in the tank and the hubs didn't pull in.

There is a lot to go wrong.

Blocked filters wont let air in to push the hubs over. Leaky pipes will not apply the vacuum.
Changing the kingpins usually blocks up the air passages inside the hub (remove black hub and blow through each spigot in turn to clear)
Leaky solenoid valves.
Wiring fault (unlikely)

Most people give up and fit manual activated hubs.

The flashing light does not affect the transfer box operation as this was a mechanical lever, if you can jam the hubs "in" the 4wd will work just fine.

ok, printed out the blog thing from this site about all the piping ect so going to give it a good looking over the next nice week end.

took hubs off, drivers side 1 was trashed, its like some 1 tried to fix a new set of rings to them and used a hammer so was all rusty in side.

going to get a new 1 and hopfully follow on from there

well replaced the drivers side hub with the 2nd hand 1 i got for £20 delivered was in much better conditions than old 1, had a good look today in the engine bay took battery out removed the fuse box bracket the lot.

firstly i was getting vacuum from the manifold, i take it thats constantly sucking, took the blue valve thing off again guessing its a 1 way valve. the tubes seem to take some pulling to get off that black plastic bit where all these rubber tubes are connected its there an easy way to do this or is it simply pull til they come off?

Any way when you follow them down there is like a big cross section or rubber tubes with 1 going in to some sort of grey valve that has a little filter on the side ( please can you let me know what this is and if this can be faulty/broken).

2 more pipes feed to 2 blue like relays which i couldnt seem to disconnect the wires from what are these and can u take them off if so how and what with. again if they do come off should they have any current through them when the 4wd system is engaged?

i have managed to find an ex suzuki mechanic to come give me some pointers on the system and what I'm looking at but guessing with out spending a few hours on it and really looking through the system he's not going to be able to see much more than i was.

Can some 1 also tell me what the solenoinds actually look like to get the multimeter on to again am looking at the diagrams from here www.bigjimny.com/images/documents/Check_the_vacuum_system.pdf
or any other pictures that people can link would be great

thanks guys, think my option might have to be to take it to the stealers and get them just to fix it. but still determined to crack it myself