My 4WD is not engaging. Front drive shaft turns free in 2WD mode. If I put the hubs to manual and leave the transfer case in 2 wheel the drive shaft doesn't turn which is telling me the hubs are working mechanically. If I put the tranfer case in 4 wheel and the hubs in auto the driveshaft doesn't turn but the hubs don't engage telling me it's not the transfer case. I'm guessing it's either electrical or vacuum. Question is where do I begin looking?
4X not engaging
- Thread starter carm
- Start date
atk
Moderator
so 4 wheel drive works when you lock the hubs manually and the transfer case in 4 wheel drive?
1-try checking the vaccum lines going down to each front wheel....
2-can you hear the vaccum pump under the hood(should be in right inner fender area, but if your heater/ac functions working properly, probaly not the pump)
Welcome to SDD....
1-try checking the vaccum lines going down to each front wheel....
2-can you hear the vaccum pump under the hood(should be in right inner fender area, but if your heater/ac functions working properly, probaly not the pump)
Welcome to SDD....
95_stroker
Jefe
If the ESOF is working (or you have one of the manual shift transfer cases still) then you are looking for a vacuum problem. Start at the hubs and trace the vacuum line back to its source. You'll find the leak.
Thanks Guys. Can't hear the vacuum pump but maybe I just don't notice it with the engine noise. Tried tracing hoses best I could, the way they're run is difficult, and didn't see any obvious breaks. Heater,AC, controls all work fine.
atk
Moderator
what i would do is, using a vaccum guage, check for vaccum down at the lines where they connect to back side of the knuckle(make sure you have it in 4wd). if you have vaccum there the hubs could have a problem in the auto mode. if no vaccum, you may have a broken or a loose vaccum line somewhere. possibly could also be the vaccum switch that is triggered when put truck in 4wd so it can send the vaccum down the hubs....hope this helps
no-red 6 0
Senioritis
i don't know if there is a way to test it, but there has to be cuz ford said that was what the problem was..--but i did replace mine. it is exactly where you said it is - passenger fender w/ hoses into it. iirc $35 or so and solved my issue too. got it at ford.
kenholl
Its my side of the garage
Try what ATK posted earlier. Check your a/c vents. Switch it from floor to defrost to dash vents. If the air moves with the switch, the vacuum is working...
If you have a vacuum pump/gauge and see vacuum to the knuckles the next step is too use the pump attached to the knuckle. Apply vacuum to the knuckle side and see if the hub engages then, if not the likely cause is the vacuum seal on the stub axle shaft, they last for maybe 75k miles on a good day. After broken vac. lines at the knuckle they are the most common failure I have repaired.
