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Discussion Starter · #1 ·
My truck: 2018 Lariat, 3.0L, FX4

I recently added a 2.5" level kit to my truck. Upon reinstallation I had observed my front axles were remaining connected to the wheel hub while in 2wd & engine running. So I decided to do a brake & 4wd vacuum check.

In 2 wheel drive:
From the vac. pump to the booster vac. reads 29 inHg. From booster vac line T to IWE solenoid it reads 29 inHg.
On the output side (top male fitting) of the IWE solenoid it reads 0 inHG. Checking voltage I have a solid 14.2 volts on the white wire and the other wire I have 8.x volts. Meter was grounded to the body ground point located just above. The voltages remained constant when selecting 2wd or 4Hwd or 4Lwd. ???

I am hoping someone can help me understand why there is no low signal to the IWE solenoid when selecting different drive modes?

My understanding and I may be incorrect. While in 2wd the vacuum should be above 24inHg and holding steady all the way down to the individual IWE's. The vacuum being applied to the hub spring and prevents the axles from locking.
Then when selecting 4wd vacuum is removed via the IWE solenoid and the front hubs then lock in.


Thank you
 

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@Chad1903 - From my understanding, the axles are always spinning for AWD on 4WD Lariat and above trim levels = this is why the fuel mileage is less for 4WD Lariat and above trim levels due to the parasitic loss of axles always spinning to be able to apply AWD if the computer senses abnormal wheel rotation on any individual wheel.

Just wondering if this Lariat and above trim level caveat forces certain states regardless of one might think it "should" work.

Unsure if this might be the reason, but I do however respect your vacuum pressure testing & posting here to the forums.

BTW - nice looking truck = I really like the two-tone with the blue & tan (I had a 2000 Expedition with the same color scheme)
 

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I believe everything both of you have said is true. It is a simple system, normally both front wheel ends get vacuum and are disconnected until vacuum is removed and wheel ends engage the axle. To complicate things, Ford does not want to spend a dime trouble shooting the system so they have a TSB to dealers instructing them to simply cap the vacuum lines and give it back to the customer. Makes sense on a dollar level but that is all. In other words I doubt a dealer will assist.

Here is the TSB: https://static.nhtsa.gov/odi/tsbs/2020/MC-10181917-0001.pdf

Issue: Some 2003-2020 Expedition/Navigator and 2006-2020 F-150 non-Raptor vehicles equipped with a TOD transfer case may exhibit grinding/clicking/ratcheting noise from the front wheel area. This may be due to partial engagement of the integrated wheel ends (IWE). To correct this condition, follow the Service Procedure steps to remove and cap the vacuum supply line

Service Procedure NOTE: This procedure permanently engages the IWEs without affecting any other functions. 1. Does the vehicle have a mode select switch (MSS) that includes a 4-wheel auto (4A) option? (Figure 1) (1). Yes - proceed to Step 2.
2. Locate the vacuum supply line between the source vacuum and the IWE check valve. Refer to WSM, Section 308-07A. (Figures 2-3)
3. Remove the vacuum supply line.
4. Install the vacuum caps at the IWE check valve and the vacuum source


I know yours is not grinding but I think this is the path Ford is going on all these IWE issues. Hopefully you can get this resolved to your satisfaction. Jmperlik is correct in all he says, especially about your beatuiful truck!
 
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Discussion Starter · #4 · (Edited)
@Chad1903 - From my understanding,
I believe everything both of you have said is true. It is a simple system,

Thank you both for responding! jmperlik, If hubs are disconnected you are correct the axles will still rotate when in 2wd, due to the mechanical nature of the front differential design. I also understand your comment about higher trim level trucks may be doing things discreetly that we typically would not expect, for example being in 4 auto mode. In my situation it is not a matter of the hubs locking or disconnecting. I simply want the system to function as it was designed. Personally I don't feel that expectation is unreasonable. I have already verified the mechanical side is in full working order and have traced the issue back to the IWE solenoid. I forgot to mention this yesterday the solenoid has 52ohms across the coil. As I mentioned previously the voltage on the input plug is constant. This explains the solenoid state, however the cause of the issue has yet to be found. Which at the moment I am leaning towards this being a factory electrical control problem or a harness miswire. Either way I am planning on dropping it off at Ford probably in a few days. Tomorrow I have an appt for a front end alignment.

Dunrollin - Could you not had given me better news? I'm joking. Actually you may very well be correct the dealership may say they can't help me. Reading your TSB link I notice they do not mention the root cause and only blame "partial engagement" as the problem. Technically speaking my hubs have not clicked or grinded, so does this TSB apply to my situation? I would argue that it does not.
I understand the solution Ford is suggesting however in my humble opinion it adds additional wear to components while reducing fuel economy. I can easily see how this could become if not already a class action suit.

Again thank you both for responding. I want you to know I value your input or anyone else's. 😃

btw- thank you for the truck compliments. Its my dream truck - sadly I am contemplating on selling. Simply bc my needs have changed and am finding it difficult to justify having a platinum lvl Lariat.
 
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