4WD won't engage, 99 Rodeo LS

Last night I got stuck in my own driveway. My dash indicated the 4wd was activated but no drive to the front axles. When I left home, it was definitely working as I tossed it into a ditch on a snowy dirt road on the way to my hockey game and walked right out throwing roostertails from the front wheels. On the way back, no go. The light will indicate engaged and disengaged but no drive.

I did wash the unit and hose down the undercarriage the day before. When I left the next day, the temp was about 30 but dropped to zero by the time I lef to go home. It remains at zero today. I turned on the heat in the garage to see if there may be moisture somewhere that has frozen any actuator/switches on the transfer case/diff. Waiting to see.

I've had it for a year but have not gotten around to checking front fluid levels. Is this a viscous unit ( I don't have a Haynes for this)? Is it possible that the diff won't engage because of lack of fluid pressure? Where can you check the fluid levels? WHat are the fluid specs?

Any help appreciated, I got a great starter solenoid fix here, hoping for another.

Darwin

Check your electric shift on the fly actuator. It's mounted on the drivers' side front axle tube. It's common for them to hold moisture & corrode or freeze up. You should be able to hear it 'buzz & click' if you just put the ignition key to 'on' & press the 4x4 button.
G/luck
Joel

Thanks. Actually, I didn't think to check that before I put it in the garage. I did check it after about 6 hours in above-freezing temps and I could hear the solenoid operate. I'm going to try and dry things out and wait for the outside temps to rise before I try to run it.

THawed out the truck, still no front drive. I can defintely hear the solenoid (?) moving when the dash switch is activated/deactivated.

Everything under the truck looked clean and dry. Without a manual, I'm not really sure I can tell which contacts are for the shift on the fly actuator.

It appears that I do get some limited slip from the rear wheels when I try to activate the 4WD.

I'm not sure if it matters but I didn't mention that this is an autobox. Can someone post how to check the fluids? Does this unit operate on fluid pressure?


Thanks for any help, getting desperate as there is much snow on the way here.

These trucks, like most any 'part-time' push-button 4x4 use a front axle disconnect to lock the front axle solid in 4x4. There's no fluid pressure involved at all. Here's your SOTF actuator: http://www.planetisuzoo.com/data/articles/65/shiftmotor-me.jpg
2 things happen when you press the 4x4 button. 1) an electric clutch in the transfer case turns on the front drive shaft, sending power to the front diff. 2) SOTF actuator locks the front axle solid. You'll see that you have no ATF dipstick for your 4L30E auto tranny. There's TONS and tons of posts on this board & others in regards to checking ATF level & servicing these 'sealed' units. It's alotta fun :nutkick: If you have a "G80" on the firewall option code tag, you have a limited slip rear diff. Factorty front diffs are open.
G/luck
Joel

With the engine off and the unit in gear:
I should be able to engage the front driveshaft and eliminate or verify a clutch fault if I activate the 4WD. ie; if the driveshaft still spins freely then the clutch has not engaged, Correct?
if this is true and there is no clutch fault then the trouble would lie with the actuator. Does it work by having the diff gears engage the front axles?

... Does it work by having the diff gears engage the front axles?

Not exactly. The passenger side front axle shaft is live from hub to front diff (spider gears) all the time. This does not cause the input to the diff to spin because it's a open (non posi or limited slip) diff. The drivers side axle is two short shafts that can be splined together or disconnectied by the SOTF actuator. Only when the drivers side is locked & the front axle is live from tire/tire will the diff input spin.
G/luck
Joel

These trucks, like most any 'part-time' push-button 4x4 use a front axle disconnect to lock the front axle solid in 4x4. There's no fluid pressure involved at all. Here's your SOTF actuator: http://www.planetisuzoo.com/data/articles/65/shiftmotor-me.jpg
2 things happen when you press the 4x4 button. 1) an electric clutch in the transfer case turns on the front drive shaft, sending power to the front diff. 2) SOTF actuator locks the front axle solid. You'll see that you have no ATF dipstick for your 4L30E auto tranny. There's TONS and tons of posts on this board & others in regards to checking ATF level & servicing these 'sealed' units. It's alotta fun :nutkick: If you have a "G80" on the firewall option code tag, you have a limited slip rear diff. Factorty front diffs are open.
G/luck
Joel

I believe this is the culprit of my lack of 4wd, does it just need to be cleaned or should/can I replace it? Where can I buy one?

I was replacing my shocks this past weekend and took the time to listen to what happened when I turned the 4WD on and off. The transfer case seemed like it was engaging properly, but there was no sound coming from the front axle where that motor should be. I just got my rodeo running again after letting it sit idle for over 6 months. So now I want to make sure I get everything in prime condition. Expected final cost: $4000

Holy post reserection batman!!

Start with the tests in THIS POST (http://www.automotiveforums.com/vbulletin/showthread.php?t=687249) to make sure its the actuator thats bad.

There is no real procedure for rebuilding or repairing them. The factory manual says to replace it if its bad. You might be able to get it to free up by removing it and moving it by hand. Can get a used one from a salvage yard but no guarentee that it would be any better. New ones from isuzu arent cheap though.

Holy post reserection batman!!

Start with the tests in THIS POST (http://www.automotiveforums.com/vbulletin/showthread.php?t=687249) to make sure its the actuator thats bad.

There is no real procedure for rebuilding or repairing them. The factory manual says to replace it if its bad. You might be able to get it to free up by removing it and moving it by hand. Can get a used one from a salvage yard but no guarentee that it would be any better. New ones from isuzu arent cheap though.

You ain't lying. After some foot work (read: searching on the internet and a few phone calls) dealership in Austin tells me it's $164.80 and isuzuparts.com says it's $112.97

Sorry to not read the topic fully, I was going to finish reading it when I get home from work. I'm betting I've got the same problem as tnobori1. I really want to get this fixed before I go down to the coast on the 17th!