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[Solved] 1982 Isuzu Trooper - Junked Bush Truck - 4x4 Not working at all. - UBS13

728 Views 16 Replies 5 Participants Last post by  Skittles
Hi guys, I have a hacked to pieces 4x4 Isuzu bighorn/trooper (Holden Jackaroo). Its old as the hills and seems to have an extremely uncommon engine in it (UBS13, G200z petrol 2L)

It is a manual transmission, with a manual selecting gear stick for 2, 4H and 4L. It also has manual lockers.

The problem I'm having is it doesn't seem to be going into 4x4 no matter what I select. I can feel a small crunch when going into 4H or 4L. but its simply not engaging. Now I have been looking at forums for a week now trying to find useful information. I have come across many regarding SOTF vacuum issues etc. However after comparing all of those photos and walkthroughs, I'm confident my truck is too old to have this system. I also get no 4x4 light on the instrument cluster. Although I don't even know if I should have one as its quite an old model.

This thing has had a HAAAAAARD life. It also has about half the wiring chopped out of it.
If anyone could give me any info on parts to check, or perhaps any information on how to hardwire/bypass solenoids to make it always engage 4x4? (it never sees any roads)

Any help or ideas are appreciated.

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Goodness, you weren't kidding about it having a hard life.

The transmission behind that G200 should be an MSG4. Unless someone has retrofitted it (I have no idea how they would do such a thing) there is no SOTF on that Trooper. You likely broke a gear in the transfer case. You basically have to pull the transmission apart to fix it as the transfer case is an integrated unit. You can easily verify it is the transmission by getting all four wheels off the ground and seeing if the transfer case will spin the front prop shaft. I will mention that this method can tell you if the transfer case is messed up, but can also give a false positive result as many transfer case issues only show up under load (meaning you will have to get it stuck in 2H).
I think it's important to add that first gen Troopers/jackaroo used 2 different auto locking hubs.. The US didn't have the trooper until 1984. So I can't say when this changed was made. The earliest type are made by Aisian and later years used Isuzu own inhouse designed locking hubs. They look completely different from one another.

If your hubs look the one in the photo, you do have Aisin auto locking hubs. Testing for proper operation of both sides will need to be added as possible cause of why your 4x4 is not working.

View attachment 127488
The USA models got the Aisin auto locking hubs as the only option from 1984-1987. In 1988 with the introduction of the 10 bolt front axle and hub redesign, Isuzu went to their own auto locking hubs and Aisin manual locking hubs for the newly introduced automatic models. The Isuzu autos came on all vehicles except the 4-cylinder automatic until the end of the first gen Trooper in 1991. From then on it was only Isuzu autos on traditional transfer cases and drive flanges on the SOTF systems.
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