I have 1 97 F150, manual 4WD shift and no hubs. When I shift into 4H or 4L I can feel the difference in the drive train but front wheels do not engage. Dash light says in 4WD but definately no front end power. Looked thru fuses and currently waiting for better weather to get underneath and check (10 degrees and snow, no garage). Has anyone else had this problem? I have read numerous posts on electronic shift but haven't found any on manual.

Thanks All!

 

As far as the front diff engagement, it is the same for MSOF as it is for ESOF. Could be the engagement solenoid, vacuum leak to the vacuum motor, bad vacuum motor, or broken or stuck engagement fork.

 

this May Sound Dumb But Try And Disconect The Batery And Then Try It my Kid Thougt It Would Be Cool To Flip The 4x4 Switch Off And On 50 Times,same Thing Happened To Me

 

Inspect vacuum line by battery. I had a massive vacuum leak due to acid.

 

Mine is manual shift though... do I still have vac lines?

 

As I stated, the engagement of the front axles at the diff is no different between MSOF and ESOF. The big difference between the 2 is that on ESOF the transfer case is engaged by a motor. Has nothing to do with the front diff engagement.

 

Last week I replaced my cracked vacuum lines. I used a vacuum gauge to diagnose the problem. Do you have a vacuum pump with a gauge? You will also need a multimeter or a test light and a 10mm wrench or socket to remove the cover on the actuator motor. The first thing to check is for power to the solenoids. Behind the battery on the firewall. The one closest to the fender controls axle lock up and the other one unlock. The white and light blue striped wire should have power in run. If not check the fuse. Fuse #23 10amps in the cab. The PCM grounds the solenoids to control axle lockup and unlock. The red wire is the ground for the lockup solenoid. Either test it for continuity to ground with 4x4 engaged or connect the test light to the terminals on in the connector.
Do the same with the other connector except with the lever in 4hi. If this checks out you need to test for vacuum. I'll get back with a diagnostic procedure.


JMC

 

Here is a picture of the solenoids.

JMC

 

I appreciate all the input. Hoping it will get above 10 degrees this weekend so I can run tests. Thanks to you all and I'll give an update once I've tried everything!

 

Might want to look at this thread too. There are a few more reasons why it would not engage the front diff.

https://www.f150online.com/forums/sh...d.php?t=293031

 

I had this same Problem on my 01 and I changed this vacuum solenoids... The ones in the pictures Above and now I have 4x4 again. Got the solenoids from a wrecker for 5 bucks.

 

As kingfish 51 pointed out in his posts, thanks btw, test the vacuum using his method.

FWIW both solenoids function using the same principle. When engaged the solenoid flows vacuum from the bottom nipple to the top nipple which is then sent to the actuator motor. When disengaged the bottom nipple is sealed shut so the vacuum in the system is not vented to atmosphere. The top nipple then vents to atmosphere releasing the vacuum in the actuator motor so it can change position.

JMC

 

I think I need to throw my hat into this thread I think my problem is the same or similar. I have a 98 4x4, but i am convinced I have no 4x4. Currently I switch my **** to 4 hi, the switch seems to click five times and then the 4x4 is illuminated on my dash. However the light doesnt go off unless the truck is shut off. My friend swears he drove it and he says its engaged, but we got 5 inches today and I was fishtailing all over the place on flat ground. I have 400 lbs in the back and kick *** tires (REVO) and I have already replaced the transfer case motor.

HELP PLEASE

 

Jack and support the front wheels off the ground and put the truck in 4Hi. get under the truck and try to turn the front drive shaft. If it doesn't turn the t-case is ok. If it turns the t-case is not engaged.

JMC

 

How far, how much travel should the shift fork have?