pretty much bone stock truck. '98 4x4.

I started ripping into the hvac system since I could only get air through the defroster. I can still get hot/cold, but only through defroster. I can get the mix setting, but only if I ref the engine up.

I got my vac gauge out and started tracing it back. 4 inches of Hg at the diaphram that controls floor...which would only crack it open. I can move the actuator just fine. If I use my vac gauge to create a vacuum, it works fine. Traced it all the way back to the vacuum resevoir...still only 4 inches Hg. I checked the source vac line, there is 17 inches there. There is a t-piece to send vacuum to the cab and one line to the 4x4 system. If I disconnect the 4x4 system, seal it up nicely, HVAC works as advertised. So what is this guy? I'm guessing it is the diaphram to engage the PVH system. I'm pretty sure this is the source of my leak.

 

called the dealership up and they said it was the 4WD Vacuum Solenoid Assembly....75 bucks. I'm pretty sure the diaphragm just has a hole in it.

I've got all the lines tucked away...will running around without a wheel liner cause much of a problem??

 

I would buy a set of AVM's and just cap the lines to it.

 

Thanks for the suggestion...but I think just replacing that one part is less work and is cheaper.

 

i would also get the manual locking hubs and do away with what wasn't needed.

 

I was thinking about the AVM hubs as I was coming home from the dealership. Going to AVM hubs vs getting the replacement 4x4 vacuum assembly still wouldn't solve the problem since the 4x4 vacuum assembly would still have a vacuum leak...I'd still have to get this piece to satisfy the 4x4 control computer. The computer still needs to think that the system has vacuum. I've capped the vacuum off before this assembly, cutting the whole 4x4 segment from the vacuum system so that my HVAC has enough vacuum to operate. Doing so pisses the 4x4 computer off and my hi/low lights have been flashing.

 

one of the lines from that vaccum assembly goes to the vaccum resevoir. connect a vaccum hose to from that assembly to the vaccum resevoir (little black ball, should be mounted on inner fender) and test her out.

 

...I did...the T that splits between HVAC and 4x4 is after the resevoir. once I disconnect and plug the line that goes to the 4x4 system...I get full vacuum to the HVAC. If I connect my vacuum gauge to the 4x4 system and create a vacuum with it...it will not hold a vacuum.

 

well, I've got the part replaced and have all the soft vacuum lines replaced...and now my hi/low lights are flashing at me...everything is connected. I did get it to work for a while after I disconnected the battery and started it up in 4hi...but after two short trips, it is back to flashing. I can hear the module clicking 3-4 times in the dash, then the lights flash.

With the new part installed, I have great vacuum at every point I've checked.

 

Hi low lights are a sign of the tcase stuck between shifts. Unrelated to the vacuum issue.

 

I've been a bit busy to really look at this yet. I had to go out to run some errands and noticed that something was engaged...it kinda felt like it was in 4hi.

I got home and jacked it up real quick with the rear wheels on the ground and spun the driver's wheel...the front driveshaft spun but the passenger wheel did not. I spun the passenger wheel, similar result...front driveshaft spun, but driver side wheel did not. Front end is an open diff.

The hubs are engaged and I'm assuming the transfer case is in 2WD since the driveshaft spun freely. I still plan on looking at the motor, but would the motor still be related? Maybe the system has tried to go into 4wd, motor got stuck, then system failed in 4wd mode?? Trying to understand the system.

 

You can try and reset the battery, it cant hurt.

You can pull the shift motor and shift the tcase with pliers to verify your in 2wd.

I see 2 options clean the motor or replace it.

Servicing A Transfer Case Shift Motor

If you have a brown wire going into the tcase you need to remove it from the harness plug to get this motor out of the truck.

 

I pulled the negative cable today and got it completely in 2WD now. I'm taking a big trip for the holidays (not in the ranger), so I'm going to try to pull it before I leave and rebuild/clean it at my dad's shop. He's got way better tools.

 

over the holidays, I rebuilt the shift motor. Got it all back together and tried to install it tonight.

First thing I noticed was the keyed shaft was not oriented right. So I tried to turn the shaft counter clockwise to get it into position. It moved into just past 4hi, but did not want to go into 4lo....it felt like a rubber band kept turning it back to 4hi. On one of the attempts, it rotated back hard enough it snapped back into 2hi. I tried again, it went past where it says 4hi. Now it wouldn't go to 4lo or 2hi.

I got pissed and took a test drive to see if it would drive like that...it should since the hubs would not lock. It did drive, but when reversing and turning a bit, the drivetrain would really bind. Once I drove it forward, it would unwind and be okay...but if I turned I could feel the drivetrain bring the engine down a bit. Got it back home and decided to see if I could pull the motor apart and move the gear inside to match the motor position to the tcase shaft position. When I went to try to move it, it easily swung to 2hi...I put it in that position and moved the gear inside the shift motor to match, then put the blue cap back on, aligned to the shift motor case as before. So now I have the dial in 2hi, my lights don't flash....but it still feels like it is trying to be in 4hi.

should I give up and just get a newer tcase?

 

Pull it back apart and see where you are, maybe its misaligned.

Sometimes to get into 4lo you need some drive-train movement. I'm not surprised you could not get it into 4lo with out the engine running. I doubt you have damaged the case. but its possible. I can tell you pulling the case is not a fun job. The top bolt requires a ratcheting box end wrench to remove. You can pull the case without a jack if you dont mind bench pressing it on and off. A friend will greatly help.

 

now that you say that, I was in 1st gear instead of using an ebrake.

I'll take it back off (getting good at this), put it in neutral and try again.

on the upside, it felt like a 2wd today.

I really appreciate the help.

 

just to check that I got the motor back together correctly, if I applied battery 12v to the orange/yellow wires, shouldn't that turn the motor??

I saw Advance has reman'd motors for 72 bucks after core charge...looks tempting.