Ok so my 4x4 is acting weird. In the summer it went into 4wd LOW and stayed there, could not get it out, took it to my mechanic and he said the shift motor in the transfer case was already a used one and was installed incorrectly, so we put in a new one. It did shift in and out of 4wd at the shop, although it was very slow in changing from hi to low. A few days later it stopped working all together, but at least I was in 2wd so I didn't care at this point.

Throughout the winter when I wanted 4wh I would try get it to work but to no avail. Then the other day it went into 4wh but now it won't come out again. If I remember correctly when I took it to the shop last year, the mechanic did say I wasn't getting any power to the shift motor, but after they changed the motor it was getting power.

What could cause the shift motor to stop getting power? Is there a relay for the ESOF, other then the vacuum one? If I unplug the vacuum one on the firewall, the 4x4 HIGH light goes off but it stays in HIGH.

I searched everywhere and could not find an answer. Thanks guys

UPDATE: I don't mind having to drive in 4wH but it feels like its binding some times, then it goes away, but now the binding is back with heavy vibrations, so not even driveable at this point, does this mean the front axles are not fully engaging? Almost feels like I am driving with the front brakes on.

UPDATE 2: I removed the vacuum line to see if maybe it was not fully engaging into 4WH, and then I tried to see if it would shift into 4WL, it clicks into 4WL but now won't come out. I am going to replace the vacuum solenoid to see if that works, it appears I am getting power to the shift motor, so hopefully its just the vac solenoid.

I did find the post on "Everything you need to know about the IWE", that helped a lot.

 

OK I replaced the vacuum solenoid today and that had no effect on the 4WD. It is still stuck in LOW, I don't think its the IWE's because it only went into 4WD when I changed the ESOF, its back to no getting any power to the shift motor on the transfer case, thats what I am thinking as that was a problem before.

What would cause no power to get to the shift motor?

 

Found the fuse panel in the engine compartment, there are 2 relays associated with the 4WD, I swapped them out with the High beam relay ( same part) and the high beams work with both of the 4WD relays, so rules out the relays, now I have to find out why my shift motor is not getting power.

 

A couple of things to think about:

1) Have you verified (with a test light) that the ESOF motor is not getting power?

2) Unhooking a vacuum line from an IWE will lock that particular wheel hub to that particular half shaft. That's not the same as being in or out of 4 wheel drive at the Transfer Case.

3) The light on your dash (either 4Hi of 4Lo) comes on when the Transfer Case shifts.

4) Are you putting the truck in Neutral when you try to shift in or out of 4Lo? The Owner's Manual will tell you that you have to. Sometimes you might even have to be on a slow roll.

5) As for you feeling axle bind in 4Hi or 4Lo, of course you will. That's why you should never drive in 4 WD on dry pavement.

 

As for the ESOF not getting power I am going by what my mechanic said in the summer, he said it was getting no power to the shift motor, but once he put the new motor in the power came back.

I heard it go into 4WL when at the case, heard the clunk, so I know both wheels are in engaged.

As for the dash light, yes, it only comes on when it shifts at the case, before the other day when I would change the ESOF ****, it would not go into 4WH or low and the dash light would not come on at all. Seems like the switch is not communicating with the shift motor, but then it all of a sudden did work, thus my problem now.

Yes putting the truck in neutral to try to get out of 4WL, even tried backing up for a distance, as some suggest, nothing.

A knew there would be some bind when in 4WH and of course in 4WL, but the binding comes and goes, which didn't feel right, but most be due to the dry pavement, cool.

I appreciate all the help. I am going to try and unplug the shift motor and plug it back in, as I said before when the shift motor was changed power came back, so maybe its a short in the wiring harness at the motor. I'll check the wiring when I am under there as well.

Thanks again.

 

Let me address some of your points:

"As for the ESOF not getting power I am going by what my mechanic said in the summer, he said it was getting no power to the shift motor, but once he put the new motor in the power came back."

I wouldn't trust what somebody said last summer. I only trust what I find when I'm actually working on something. I pretty much doubt putting a new ESOF motor in caused the power to come back.

"I heard it go into 4WL when at the case, heard the clunk, so I know both wheels are in engaged."

Remember, the TC shifting and the IWEs (kind of like hubs) locking are separate events.

"As for the dash light, yes, it only comes on when it shifts at the case, before the other day when I would change the ESOF ****, it would not go into 4WH or low and the dash light would not come on at all. Seems like the switch is not communicating with the shift motor, but then it all of a sudden did work, thus my problem now."

Still could be that the ESOF motor is unable to shift the TC.

I think you need to separate your TC shifting issues and you IWE lock / unlock issues and deal with them appropriately here.

 

ok good point. I am going to try and find a vacuum pump to test the IWE's and see what happens, will also check wiring as well.

 

Also check the IWE Solenoid up on your passenger side firewall. The new & improved style has a "hat" that prevents water from running down from the cowl and getting into the vacuum lines. (When it does that, it will eventually wipe out your IWEs and possibly the Check Valves.) If you do have the old style Solenoid, replace it. But, simply replacing it may not solve all of your IWE problems - particularly if water already got into the vacuum lines.

 

yeah it already has the new version of the solenoid, the guy I bought the truck from 2 years ago replaced the IWE's and the solenoid then. I bought another solenoid yesterday just to check and it did not help, so now I have a spare one, haha, they are cheap so no big loss.

I unpluged the shift motor at the TC and plugged it back in, doesn't seem to be any loose wires, still waiting to get a vacuum pump to test the IWE's at the hubs. I don't think they are the problem since this problem happened before and only happens when the ESOF actually gets the shift motor to work. Shift motor is brand new as well.

Gonna double check them anyways to make sure.

I notice the older models tend to have bad GEM modules, does the 2005 have one? From my research it doesn't appear they do, at least no one has posted about it, all searches come up as pre-2004 that have the GEM module.

I am wondering if my TC is messed up and the shift motor doesn't have enough power to shift the TC? Possible? Apparently my old shift motor that was replaced in the summer was installed incorrectly, not sure how as I did not see it, but it was already a used shift motor from the auto wreckers that was in there when I bought the truck.

How often do the check valves fail?

 

OK I wasn't able to do much today, but I can confirm the switch works fine, I can hear the relay click when switching the ESOF **** from low to high to 2wd, but still nothing at the TC. Hopefully tomorrow I can get a vac pump to double check the IWE's, also going to try and lift the front end off the ground and try to shift it, heard that helps sometimes.

I think I asked before but this all started when a last year when I shifted into 4WH on the highway, I have since read you should not shift on the fly above 55mph, what could happen if that was the case? I don't think I was above 55mph but I can't remember honestly, I know it was bad weather on the highway and there was slower traffic in some areas.

 

I haven't found a vacuum pump yet, but what I did today was remove the shift motor and try and get it to shift without being connected to the TC. NOTHING! I called my mechanic and he thinks the shift motor may be bad, it has a lifetime warranty so he is going to replace that and see if that helps.

I manually put the TC into 2wd, but the hubs are still engaged since the computer thinks its in 4WL.

Since the axles are still engaged, I guess its as if my truck is in 4WH, meaning the front axles are spinning but the TC is not being effected, so I propb shouldn't drive it? Or is it safe to just drive to work, which is only about 5 miles each way. I am taking the truck to my mechanic ASAP though.

 

As long as the transfer case is not driving the front driveshaft, you can drive it with the hubs engaged.

None of your local parts stores have a simple vacuum pump? The ones here have them as free loaners.

 

A couple of more points:

"I haven't found a vacuum pump yet, but what I did today was remove the shift motor and try and get it to shift without being connected to the TC. NOTHING! I called my mechanic and he thinks the shift motor may be bad, it has a lifetime warranty so he is going to replace that and see if that helps."

Again I'll ask, do you have power to the ESOF motor? Don't waste your time & effort replacing a motor if there's no power coming to it.

"I manually put the TC into 2wd, but the hubs are still engaged since the computer thinks its in 4WL."

Remember, the TC shifting and the IWEs locking / unlocking are related events, but not locked together. If the truck was not running, your IWEs would lock anyway. When you start the truck and have some vacuum, they should unlock.

"Since the axles are still engaged, I guess its as if my truck is in 4WH, meaning the front axles are spinning but the TC is not being effected, so I propb shouldn't drive it?"

If your TC is in 2WD, even if your IWEs are locked, you should be OK.

 

Drove the truck to work today, and then straight to my mechanics, I'll let him deal with it now. I was trying to do it myself cause I couldn't drive it to the shop, its was just too far to drive in 4WL. I am curious to see what he finds out, he thinks its the shift motor as well, its got a lifetime warranty anyways. I will update what he finds out.

Thanks again for all the helpful info.

 

Just got the truck back from my mechanic, its was just as I suspected, no power going to the shift motor on the TC, turns out the relays were intermittently working. My mechanic tested the relay's and they worked fine, but then after a bunch of tests they started acting up. I tested them myself the other day and they seemed to work when I swapped them into the high beam relay spot, but turns out they were the problem.

Only one of the two relays was bad, can't remember if it the the CW or CCW one, but we replaced both and now everything works great.

Thanks again for everyone help, great site.