help with 99 mod hilux FWD not engaging

[grnlux]

MY 99 SR5 d/cab will not engage FWD have checked out the air solenoids and they seem O.K. Has anybody got any details on the ADD system like scamtics of electrical and air layout? Have searched google but only find info for removing the ADD system not repairing, my local toyota dealer must only work on holdens as he did not know what auto locking hubs were.

[thebrunks]

Pull the motor out from the transfer case, pull it apart & see if there is moisture or rust on the shaft.

The motor engages 4wd in the transfer case when the button is pushed!

Russ

[brighty]

mate of mine has a 94 SR5 and had the same prob.... he had the transfer stripped down and it kept happening not long after it was fixed, kept giving us the shiats get'n all the way out the bush and his rig wouldn't work properly... so in the end he opted for an older manual shift g'box/transfer. Not sure what model it was out of... but he's had no probs ever since.

[killa]

http://www.toyotasurf.asn.au/techsite/add.htm

Does that help?

[grnlux]

Thanks killa this is what i was looking for hope it helps as for the rest of the site is seems to be a wealth of info thanks again

[delphisii]

Agrree with The Brunks. Bro had same thing the other day on his '97 lux. Finally tracked down to the motor on the back of the transfercase. Vent pipe had come off and allowed water to get in. This had caused a lot of corrosion on the spring assembly and the pickups in there. After cleaning and greasing it works fine. If you undo the 3 mounting bolts you can check it out on the bench. It's a bit hard to remove as you have to pull it off against the detent on the shaft. But give it a gentle lever and it will come free.
hth Wayne

[thebrunks]

My 92 Hilux did it about 8 Years ago, firstly it was intermittent, sometimes it would work & other times it wouldn't then eventually it wouldn't work at all.

I tracked it down to the motor as the front diff seemed to be engaging.

If you jack up the rear end, engage 4wd & have the gearbox in neutral, spin the rear drive shaft. If the front drive shaft doesn't turn, then it's gotta be in the transfer case.

Even if the light doesn't come on it will try to turn the motor & engage the front end

Off memory when you press the button with motor turned off & ignition on it will still work, the front won't engage with the engine off as it needs vacuum to work & this is not there until the motor is running.

Does it do it in low range??

Russ

[grnlux]

Thanks delphisii
It would apear my problem is the excact same as what you had breather pipe was busted but how do you get the motor off the back of tranny have undone the tree bolts just a bit afraid or breaking something if I lever it to hard ?