98 Passport (Rodeo) 4x4 problems...

[atomsplitter]

OK, I've got the ol' blinking 4x4 light when I try to shift into 4 wheel drive. I've done some searching on this forum (which is GREAT might I add) and this is my problem:

I've narrowed it down to the actuator on the front axle. I've got pretty good (I think) vacuum down to the actuator. I can feel it pretty good with my finger. I've gotten it to engage 4x4 with a little mechanical agitation (ie a hammer tap to the actuator) and then to disengage. I know my x-fer case is engaging the driveshaft to the front diffy. I'm thinking my actuator is a little gummed up and not moving freely. Has anyone taken thiers apart and cleaned/lubed it? How hard is it and how should I go about it? This Passport came from up north (no offense to you yankee's) and has moderate rust and corrosion on it's belly and that's kinda what I think my problem is. Any input/suggestions would be greatly appriciated...

[Gizmo42]

I cant imagine it would be too hard to take apart. I havent read through it but there is a section in the faq about this http://isuzufaq.ibctech.ca/#faq68 might give some tips.

[atomsplitter]

Yeah, I was looking through the 2300+ pages of the manual and havent found any really good expanded views of the actuator (other than electrical and vacuum diagrams). I'll probably try to take it apart tomorrow. I'll post any pics or info I come across.

I was just wondering if anyone else has disassembled it to clean/lube it. Every time I tell my wife I'll only be an hour or so working on the car... that turns into a day and a half. She should know by now!!!

[Gizmo42]

I looked through the factory manual when I got home and it says to just replace it if its bad so no service info for it.

If you cant get it free'd up you should be able to pick up a used one pretty cheap. Maybe post a parts wanted message on 4x4wire.com since alot of guys on there have done Straight Axle Swaps and probably have one sitting around doing nothing.

[atomsplitter]

When you say Strait Axle swap do you mean just putting manual hubs on or do they actually repalce the axles. I don't use 4x4 much but when I need it I want it to be there. Do you think it would be worthwhile to look into that or would it be better just to find a new(used) actuator and keep things like they are are?

[atomsplitter]

Yo Gizmo...
Update on my problem... It's not the actuator. I think it's the vacuum solonoids on the firewall. If I engage the 4x4 and unplug the vac line to the blue swith i get 4 wheel drive. then to disengage I have to plug back up the blue and disconnect the black for a few secs. Anybody ever heard of this before? I KNOW i'm in 4 wheel drive because I took it for a test run, went up a hill just a little too steep, backed back down it, put six inches of mud in my tail pipe, bent the exhaust, limped home, cut 4 feet of exhaust pipe out... Helluva day.

[Gizmo42]

Straight (solid?) Axle Swap (SAS) is when you cut out the entire front suspension and mount in a regular axle instead of independant suspension. Lost of work and money to do.

Not mine.. This is Starchilds passport..


Sounds like the actuator is working then. Check for good vacuum going into the solenoids, then check for vacuum in 2wd and 4wd on both lines going to the actuator. Check at the actuator and at the solenoids in case a vacuum line is pinched or bad.

Main vacuum line, runs to the switching solenoids (ignore the green circle)..


Front axle actuator, vacuum should switch sides when 4wd button is pressed..


4wd vacuum routing..


The VSV with blue plug is 2wd and grey plug is 4wd.

Could also be the computer not telling the valves to switch, I know of 1 on an '01 rodeo that went bad and wouldnt send the signal to switch the front.

[atomsplitter]

I've checked vacuum at the actuator. When 4x4 is NOT engages I get about 22 in. on the 2wd actuator line and zero on the 4wd. When 4x4 IS engaged I get about 18 in on the 4wd and about 16 on the 2wd. Seems to me the 2wd should be zero when 4x4 is on. I think there's not enough differential pressure to let the actuator move. Whenever I disconnect the 2wd VSV I get zero on the 2wd side of the actuator and It slided into 4wd. Does that sound like a VSV problem or a computer problem? I don't think I have a vacuum hose problem.

[Gizmo42]

My first thought was that the VSV for 2wd is sticking. But unplugging it should have no effect if thats the case, unless the movement of unplugging it is enough to cause it to free up. Try switching it into 4wd then smack the 2wd VSV with a screwdriver or something and see if that stops the vacuum on that side.

It seems that it would be odd for the computer to have both activated even if its messed up. If the above doesnt work, unplug the 2wd VSV and put a meter on both terminals of the wiring harness side plug. You should have voltage between them (I'm guessing 12 volts but not sure) in 2wd. Switch to 4wd and see if the voltage goes away. If it does then its the VSV, if not then its the computer. You can double check the readings against the 4wd VSV to be sure the voltage actually goes away on it.

[atomsplitter]

Thanks man,
It will be Monday before I can check it. I'll post what I find. I appriciate your help!

[atomsplitter]

Ok, it appears that my 2wd VSV is bad. I took it out and hooked it up to 12v power supply and the 4wd held vacuum when engaged. The 2wd never would. It leaked by whether engaged or not. Now to find one.

P.S. When 2wd is engaged neither VSV connector has voltage. When 4wd is engaged they both have voltage. Does that sound right?

[Gizmo42]

When 2wd is engaged neither VSV connector has voltage. When 4wd is engaged they both have voltage. Does that sound right?

That could be. Might be that the 2wd one is normally open and the 4wd one is normally closed. I would look for one from a salvage yard. New ones from the stealership are around $115 and sold as a pair. Or you could pm JLEMOND he usually has lots of parts around, if not he can usually find them.