I recently picked up a 2005 fx4 4x4. The 4x4LO light comes on and when it engages you hear an audible mechanical switch of gearing. The 4x4HI light does not illuminate (only on startup it does), there is no audible noise of switching of gearing but the 4x4 does infact work.

I've done some searching but no one mentions any noises.

Its seems my steps are:
- scan the drivetrain dtcs (no lights on the dash but thats what some other posts say to do)
- replace IWE

Anything else I should think of doing?

 

Tried to play around with it just now; lifted the car when the car is in 4wd-hi (in neutral and car on) the axles are locked, then put it into 2wd the front wheels are not locked to the transfer case but locked to the axles. In short the axles are always locked to hubs but the transfer case is what changes.

 

Any advice against disconnecting solenoid and putting the two ends together to give a vacuum and see if lines are no good?

 

I connected the hubs directly to the vacuum source (beside the brake booster) and the hubs DID NOT disconnect like IWE should. Does the engine not pull enough vacuum at idle is it only on engine decel that there is enough vacuum????

 

having the same issue somebody told me to check the fuses going to toni
ght.

 

2WD, engine running, wheels off the ground, the front wheels should spin free of the half shafts. Engine off or switch in 4WD, and the front wheels should be locked to the half shafts. If your truck isn't doing this, you either have an IWE problem (at one or both front wheels) or a vacuum problem (anywhere between the line off the engine to the IWE solenoid on the passenger side firewall, check valves, reservoir, solenoid, or the lines down to each IWE. I would start by checking vacuum at each IWE, one at a time, from the big vacuum line with the engine running at idle. You should have a min 17 inches vacuum. If that checks out, have someone else rev the engine and see if the vacuum falls. It should not. If that checks out, start pulling the IWEs to inspect them and the hubs.

If your 4x4 is in fact working as it should, but the only problem is that you are not getting the light on the dash when you should, that's electrical, probably in the controller, and I'm not sure what to do there. Scanning for DTCs is probably the best place to start.

 

The IWEs can fail in two ways- locked or unlocked. I had one fail unlocked so that I never had 4x4 because the front differential is open. If yours are failing locked, that just means that it will cost you some fuel economy until you replace them. It won't hurt the truck unless you hear grinding, which means they are somewhere between locked and unlocked.

Also, your vacuum solenoid on the passenger side firewall should have a rain hood over it. If it doesn't replace it. You can get them for ~$20 on Amazon or eBay. Cheap insurance and easy to replace.

 

I picked up a vacuum hand pump from a friend and tested the system, the actuators are dead, the solenoid is also dead, and the vacuum lines are in good shape (sarcasm).... I spoke to a ford mechanic and he told me that there is no major issue with having the IWE system fail worst case it will temporary get stuck in 4wd. My actuator died in locked mode, I'm going to take them apart and see if I can unseize them (my guess is water got into the diapharm and messed it up). If not I will most likely leave them as is. When I connected the iwe to a vacuum pump the pressure did not drop, so no internal to external leaks. I'm surprised ford would use a pneumatic system, VW/Audi are famous for pneumatic systems (and the failure of them!!!).

 

Not sure how it was tested, but in fact if the IWEs have failed in the locked position, you are not in 4WD all the time because the transfer case also unlocks the front drive shaft in 2WD mode. It will just cost you some gas mileage to spin the front half shafts and differential all the time until you get it fixed.

 

Ended up swapping the IWE(s) and solenoid.

The new solenoids where aluminum vs steel and the solenoid is the new type with the cover.

All works now!!!!

 

The solenoids have always been plastic (but did have a metal backing mount for the earlier and a plastic hood for the current) and the IWEs always aluminum.