Go Back  Ford F150 Forum - Community of Ford Truck Fans > Late Model F150s > 2004 - 2008 Ford F150
4x4 doesn't engage, P0171 and P0174 when switch to 4LO... IWE Solenoid? >

4x4 doesn't engage, P0171 and P0174 when switch to 4LO... IWE Solenoid?

Topic Sponsor
2004 - 2008 Ford F150 General discussion on the 2004 - 2008 Ford F150 truck.

4x4 doesn't engage, P0171 and P0174 when switch to 4LO... IWE Solenoid?

 
Old 01-25-2017, 11:55 PM
  #1  
Senior Member
Thread Starter
 
Join Date: Jan 2011
Posts: 222
Liked 13 Times in 11 Posts
Default 4x4 doesn't engage, P0171 and P0174 when switch to 4LO... IWE Solenoid?

Hi All,

An interesting problem I am having, but feel someone on here may have had the issue before.

Just recently replaced the driver side 4wd actuator. When testing the system to see if it was working, I noticed that in 2wd everything seemed to be in order (wheel spun without the half shaft, no grinding noises on test drive, seemed good to go).

However, when I switched to 4hi, the dash light "4HI" would come on but the wheel still spun freely without the half shaft. When the truck was off, the wheel and half shaft spun together as they should when vacuum is released from the actuator. When I switched to 4lo, the dash light did not come on and the check engine light came on. Pulling codes revealed P0171 and P0174.

Could these codes be caused by a bad solenoid? Is the solenoid not switching the vacuum off and that's my issue? Are there other possibilities?

Thanks all in advance!
nddragon01 is offline  
Old 01-26-2017, 05:34 AM
  #2  
Mark
iTrader: (1)
 
techrep's Avatar
 
Join Date: Jan 2009
Location: Va. Beach, VA.
Posts: 34,434
Liked 1,807 Times in 1,630 Posts
Default

I would replace the IWE solenoid on the firewall if you have not replaced it yet.. what year truck we working on ?. not sure where the lean codes are coming from.. could be a vacuum issue. You may want to inspect the vacuume box and all lines.
techrep is offline  
The following users liked this post: techrep
nddragon01 (01-26-2017)
Old 01-26-2017, 12:39 PM
  #3  
Senior Member
Thread Starter
 
Join Date: Jan 2011
Posts: 222
Liked 13 Times in 11 Posts
Default

Thanks techrep, can always count on you for some good advice.

Some clarification and updates:

Truck is a 2006 FX4 SuperCrew, the solenoid has been changed before to the new style back in 2008, but who's to say it hasn't died again... I have another on order to try tomorrow and return if not the problem.

I forgot 4LO only engages when in neutral with foot on brake...my bad. 4LO sounded like it's working this morning. I only hear one loud "thunk" like it's engaging, should there be two loud "thunks", one for each side? It also "un-thunks" once when switching back to 4HI or 2HI.

Actually spinning the hubs, I only checked the truck driver side since that was the side I replaced the actuator. While truck was off the hub spun with the axle shaft, while truck was on and in park and in 2wd the hub spun without the axle shaft (so I don't think there is a vacuum problem?), while truck was on and in park and in 4wd the hub still spun without the axle... does the truck need to be in neutral in order to spin the wheel to see it engage with the axle shaft?

Driving around town and to work today I did not hear any grinding, so I'm thinking my issue is the vacuum is not releasing, which is what led me to believe it is the solenoid again.

I'm planning to test more hopefully tonight, spinning both hubs one at a time, truck in 4HI and neutral, then truck in 4LO and neutral. Friday night testing will be with the new solenoid installed.

As far as the codes, they may be coincidental, but so not to ignore them, where exactly is the vacuum box located? Is that a short term for a specific part?

Thanks again!

Last edited by nddragon01; 01-26-2017 at 12:42 PM.
nddragon01 is offline  
Old 01-27-2017, 06:08 AM
  #4  
Mark
iTrader: (1)
 
techrep's Avatar
 
Join Date: Jan 2009
Location: Va. Beach, VA.
Posts: 34,434
Liked 1,807 Times in 1,630 Posts
Default

Go barrow a vacuum pump from your local auto parts store and test the system properly.
With the engine running this will provide vacuum to the wheel ends and should not spin your CV shafts unless you have selected 4WD and the solenoid has vented the IWE's. IWE's also are spring loaded to aid in engagement when vacuum is vented. A vacuum pump test will bring all this to light without having to toss parts at the problem.
techrep is offline  
 


Thread Tools
Search this Thread

Contact Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: