4wd occasionally

[shokenore]

As per the title the 4wd can no longer be relied upon.
Previously it was sporadic but quite honestly seldom required, even when off roading, only when getting to the really slippery or squishy bits would I think that it would be required and after sometimes a few quick clicks on the button could hear the relays clicking and then the 4wd indicator on the dash would light up.
But now it's not working.
At all.
So after a few false starts and some quite honestly pathetic attempts at fault finding I have started again.
Where is the best place to start ?
I reckon it has to be the 4wd switch.
The switch has been removed from the gear selector console and with the aid of a multimeter I have determined that the switch is not working as it should.
I have wisely or not now stripped the switch out and there it is on the table all in bits.
The contact shoe was heavily tarnished.

[shokenore]

Ok
Switch reassembled and now has good continuity, 0.3 ohm.
There is 12volts at the 4wd selector switch.
All put back together.
Test drive concludes that 4wd is not engaging.
Putting the gear selector to L4 does engage low ratio but no 4wd.



Any pointers or what to check now?
Ta

[BUSHWHACKER]

Sounds like a vacuum problem.
Check the VSVs next to the fusebox in the engine bay.
I have some spare ones here if you need them. Alternatively do the A.D.D. delete, I think there's a write-up on here somewhere.

[shokenore]

Cheers Vince
I will have a look at the VSV's tomorrow.
Am I right in saying that the ADD fork is moved by vacuum power?

And the next question IF I do the ADD delete what is the worst that will happen?
Cheers

[BUSHWHACKER]

Cheers Vince
I will have a look at the VSV's tomorrow.
Am I right in saying that the ADD fork is moved by vacuum power?

And the next question IF I do the ADD delete what is the worst that will happen?
Cheers

Correct.
Vacuum pulls the selector fork across to engage/disengage the passenger side driveshaft.
There's an actuator motor on the rear of the transfercase that transfers drive to the front diff.
Have you checked the fuses? There's a 4wd fuse in the kick panel fusebox.

Whats the worse that could happen? Your shirt sleeves will stink of diff oil!

[shokenore]

Will check the fuses again.

Then onto the VSV's

Just to hopefully get my head around them, am I right in saying that they divert the vacuum from pushing the selector fork to pulling the selector fork depending on the state required ie on/engage= 4wd and off/disengage 2wd?

So I'm looking at perished/displaced vac hoses or sticking slider fork or faulty VSV'S?
Thanks in advance

[BUSHWHACKER]

Will check the fuses again.

Then onto the VSV's

Just to hopefully get my head around them, am I right in saying that they divert the vacuum from pushing the selector fork to pulling the selector fork depending on the state required ie on/engage= 4wd and off/disengage 2wd?

Correct.

So I'm looking at perished/displaced vac hoses or sticking slider fork or faulty VSV'S?
Thanks in advance

Just remembered yours is the mighty 2.4, so check that the vacuum hoses are secure at the alternator, and on both ends of the silver intake duct (the part with EFI DIESEL on it) Do the easy checks first.

[BUSHWHACKER]

A link which might help........
http://www.toyotasurf.asn.au/techsite/add.htm

Forgot to ad this one......
http://postimg.org/image/5z5t4hku1/

Oh, and this.....

[shokenore]

Easy I like
I had such high hopes that it was the 4wd thumb button.

Update
I have 12volts at VSV's
When you apply voltage you can hear the VSV's clicking.
And you can hear and feel the air/vacuum at the VSV's vacuum tube connections when 4wd is selected.
Ramp job now so I can crawl underneath to make sure the vacuum is going to the right connections on the diff.


Thanks for the advice Vince

[shokenore]

Ok
Made good use of the lack of torrential rain today and got the truck up on the ramps to check through the ADD

By swapping over the vacuum hoses at the front diff diaphragm I can get open and closed contacts on the ADD indicator switch.
So this proves that the selector fork can move.
But I still get no 4wd lamp up on the dash.

What is worth checking next?
Ta

[BUSHWHACKER]

Does the 4WD light come on if you select L4?

If not, the the problem is with the transfercase motor either it's stuck due to water ingress or no electrical power getting to it.

There's two position switches on the passenger side of the T/case, one of them activates the 4WD light when you select L4.

There's some small diameter rubber breather hoses on the transfercase, sometimes the ends can get knocked off when offroading or just perish and drop off allowing water to get in and feck up the electrics.

[shokenore]

Cheers Vince
We will get it fixed, I have faith in you

There is no 4wd light when L4 is selected.
Looks like tomorrow will see the ramps out again weather permitting, so glad the side steps came off today.
Transfer case motor is prime suspect then.
Thanks again Vince.

[BUSHWHACKER]

There's two wires coming from the T/case motor that you can apply 12v to, to see if it's working, I let you know in the morning which ones when I get back under a truck.

[shokenore]

That's really appreciated
I have checked the weather forecast so I should be okay?

I could use a dc amp clamp to see any current flow, but I think I will be pulling the motor off anyway.
I think after 20 odd years of service it probably deserves a bit of tlc.
Is it likely to explode springs and cogs when removed?

[BUSHWHACKER]

That's really appreciated
I have checked the weather forecast so I should be okay?

I could use a dc amp clamp to see any current flow, but I think I will be pulling the motor off anyway.
I think after 20 odd years of service it probably deserves a bit of tlc.
Is it likely to explode springs and cogs when removed?

Clear blue skies here all day today, bluddie freezing now though!

I know the 3rd gen's multi-mode motor disintegrates when you remove it, not sure about the Council version. I'll do some reserch