Earlier this week I was driving on the highway for a long period of time (4 hours) and my 4x4 seemed to have tried to engage itself without me pushing the button on the dash. The result was a loud whining noise that slowed to a constant clicking noise as the front differential splines were barely rubbing together. I pulled the passenger front weel off and was able to turn the hub and make the clicking noise. I proceded to uncouple the vaccuum diaphram,from it's bracket, that controls the actuating cable to the front differential to gain enough slak,on the cable, so it couldnt pull itself into 4x4 and limp to my destination. I was told it was my vaccuum switch on my transfer case. Apparently it wasn't venting excess vaccuum completely and it built enough pressure to make the splines rub. Pulled it out and the ball/**** was stuck up into the switch. I ordered a new switch from an isuzu dealership, and the problem didn't reoccur on my trip home. Now unfortunetly, if I push the switch on my dash to enter 4x4 it doesn't. The light indicates that I am in 4x4hi and or 4x4 low and the transfer case seems to be operateing(can hear the electric motor working). Did I screw up the diaphram when I let itself pull all the slak it needed to limp to my destination? I'm going to work on it more tommorow. The diaphram in question is located underneith the batterie tray on the passenger fender(it is reatached to the bracket), so seeing it operate and having the vehicle running is going to be a chore.

Today I pulled the old vaccuum switch out. It appeared to have oil seeping around it. I assume that was my transfer case oil. I put in another vaccuum switch, one were the leads didn't spin, still no 4x4. I'm thinking if it was sucking up fluid from the transfer case would a bubble of oil case a clogg in the system?

P.S. An isuzu hombre is nothing more then an isuzu form of a s-10. I have a 4.3l v-6 vortech engine, 4L60E transmission, and a np233 transfer case.

My apologise I just saw that this should be in another section. Please move this thread if it is a problem.

Today I tried putting my truck into 4x4. After I pushed the 4x4 button and heard the transfer case click in I turned off my truck so i could pull the battery and look at the vaccuum diaphram. The diaphram was completely out and did not appear to have any vaccuum in/on it. I could pull the cable back and forth but couldn't get enough leverage to engage the 4x4 manually. I then checked the vaccuum switch on the transfer case to make sure the 3 vaccuum lines were connected all the way, they were. It seems odd, are the three vaccuum leeds on the vaccuum switch suppose to be able to swivel, because mine can. I have been sold defective parts before and the old switch doesn't swivel.

FOUND THE PROBLEM!

When the front differential tried to engage itself, the carrier connector's teeth sheard off and smashed the thrust washer(at least I think that's what it is) into three peices all exactly 120 degrees ( i measured). Because the teeth were sheard the shift sleeve could not move over and mesh the output shaft and the carrier connector together. Meaning no 4x4.