2014 F150 Extended Cab with 8ft box, 5.0L......210K miles

4wd does not seem to work when switched over from 2wd, always try to engage it at about 5 mph, dash states it is engaged, no banging noises....

Certified mechanics have installed both front actuator assemblies on the hubs in the last 6 months.....firewall solenoid also new....

Bad vacuum line to the firewall solenoid?

 

Are you SURE it isn't in 4X4? There shouldn't be any banging noises when it engages from 2 hi to 4hi. Occasionally going into or out of low range.

 

Hi Marshallr-thank you for your response, yes I'm positive it is not going in to 4wd....I understand that it should not bang when going in to 4wd....I've had the truck for 4 years, plow snow for months on end in the MI UP....I forgot to mention that it does not throw a code....however I have not gone in and checked but there are no codes on the IP....you should definitely be able to feel the difference in traction, especially on dry pavement (which is not recommended of course)....I found out the hard way when I dropped down in to a shallow ditch yesterday to grab some firewood....switched it over....nothing, however I did not check it after the new parts were put on....so maybe transfer case motor? Just read something about the transfer case clutch getting hot, or possibly roached? ...I'm open to any help and/or suggestions...TIA

 

You haven't clearly laid out how you know it's not actually in 4x4. Dry pavement, traction control disabled, full throttle, and it spins one rear tire?

Even in 4x4, you still have open front and rear diffs so if one tire is unloaded or has low traction (like in an off-camber ditch situation) the unloaded tire will just spin while the other tire on the axle sits still. If one front tire and one rear tire have low grip, the truck won't move even in 4H.

You don't mention your trim level - Lariat and up have the 4A transfer case with a clutch. If you have an XLT or below you don't have that clutch, you have a mechanical dog engagement.

The transfer case motor is pretty good about knowing that it didn't make it into the desired gear. I suppose the transfer case chain could be busted, but that would be pretty wild. Maybe drain the TC fluid and check for metal?

You can put the truck up on 4 jackstands and do the IWE engagement test.