When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So, I got a 2017 F-150 about two weeks ago, 77 k miles, great shape. Snow storm hit, I'm thinking "I can make it to my parents house and up their 1/2 mile driveway with some snow on it to check in." Well I couldn't make it up the slight hill they have. Put it in 4HI, readout said it was in 4HI, started up the hill, tires slipped a little, then got hit with "Check 4x4" and the yellow wrench. I can switch between 2/4H/4L no problem and drive around while in all of them, but the second there is a struggle and i need it "Check 4x4" shows up. When I shut the engine off and turn it back on the message is gone. I scanned it after i got the message and got hit with C1979-00 IWE solenoid circuit failure. Now I'm in the infant stages of troubleshooting, and doing a visual inspection I noticed that there are no vacuum lines hooked up to the solenoid, both lines are just plugged directly into each other. Attached is a picture.
Now, I'm no mechanic by any means, so I am looking for help/advice/next steps from you all. Who i am positive know more about this than me. Is this how it is supposed to be hooked up? I don't think so, so if it is then please let me know, and let me know why. Thanks.
Someone has bypassed the IWE control valve so that your IWEs are disengaged all the time. Even though you are in 4H or 4L, the front axles are just along for the ride. You probably need to replace the IWE control valve. You can see that someone has had the electrical connector off of the solenoid as one of the locking arms is broke off.
The Check 4x4 light comes on because the wheel sensors are seeing too much difference between the speed of the front and rear wheels when there is some wheel spin.
What 52merc said, I'll try to attach a photo as to how it's supposed to be hooked up, mystery to me why someone would that, but oh well. May, or not need a new solenoid, cheap enough at any rate. Looks like you may be missing a fitting as well.
Last edited by johnday in BFE; Feb 21, 2021 at 06:56 PM.
They may have done that because of further damage or issues you dont even know about yet!! I would take that truck right back to the dealer and make them fix it correctly and check everything else out!!!
Now that's a first!
Curious if once connected it grinds badly due to a worn out hub and IWE assembly -meaning teeth have been ground down and P/O was savvy enough to figure out how to pull continuous vacuum where many usually disallow vacuum so hubs are constantly locked up.
OP can reconnect using John's photo if so desired. If the vehicle is newly purchased and the dealership that sold it is willing to work with OP, maybe you can mention that there 'seems to be a problem with the 4x4 system' and have them look and check for codes. Keeping your mouth shut that you already know what it is.
If they fail to help, then mention they sold you a vehicle with an inoperable 4x4 system on purpose...whether or not they know it.
4x4 Intermittent issues
I'll try to attach a photo as to how it's supposed to be hooked up, mystery to me why someone would that, but oh well. May, or not need a new solenoid, cheap enough at any rate. Looks like you may be missing a fitting as well.
