4lo inoperative
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2nd Gear
Joined: Jun 2023
Posts: 2
Likes: 0
4lo inoperative
Hi all,
First F150, first post. Believe it or not I was tired of the reliability problems with my Tacoma! Anyway I have a new-to-me 2014 F150 STX 4X4 5.0, 9.75 rear with e-locker, 86k miles. And I am on to my first repair already...
I cannot engage 4lo. Yes I know the proper procedure re: neutral and <3mph, and that rolling back and forth or turning the wheels can be helpful. 2wd works and 4hi works; I can switch back and forth between the 2 readily. When I shift to 4lo, the t-case motor turns and the instrument cluster confirms 4lo is engaged. But the truck will not move. It is like the transmission won't engage in that mode. I've lifted the truck into the air, and when in neutral, I can shift into 4lo. getting underneath, front and rear drive shafts as well as front half shafts are all locked and can be turned by hand. but when I shift to R or D, nothing but the light grinding of something spinning can be heard within the t-case. The truck thinks there is engagement - cluster reads 4lo and even the speedometer moves and gear #'s change if I press the gas pedal. If I go back to 4hi, again the entire driveline is locked, and putting it into R or D results in all 4 wheels actually spinning and no grinding sounds whatsoever. With the t-case motor unbolted, it responds to the dash switch commands by moving into any of the three positions. And using ForScan, there are no TCCM module faults. So I'm being led away from the motor as the culprit. Since I can readily move between 2wd and 4hi, I'm led away from thinking it's a vacuum issue. Any ideas out there? Every ESOF 4x4 system I've ever had has managed to crap out in one way or other but wish as I may, the levers are never coming back
FYI I have a double-post on the F150 forum
First F150, first post. Believe it or not I was tired of the reliability problems with my Tacoma! Anyway I have a new-to-me 2014 F150 STX 4X4 5.0, 9.75 rear with e-locker, 86k miles. And I am on to my first repair already...
I cannot engage 4lo. Yes I know the proper procedure re: neutral and <3mph, and that rolling back and forth or turning the wheels can be helpful. 2wd works and 4hi works; I can switch back and forth between the 2 readily. When I shift to 4lo, the t-case motor turns and the instrument cluster confirms 4lo is engaged. But the truck will not move. It is like the transmission won't engage in that mode. I've lifted the truck into the air, and when in neutral, I can shift into 4lo. getting underneath, front and rear drive shafts as well as front half shafts are all locked and can be turned by hand. but when I shift to R or D, nothing but the light grinding of something spinning can be heard within the t-case. The truck thinks there is engagement - cluster reads 4lo and even the speedometer moves and gear #'s change if I press the gas pedal. If I go back to 4hi, again the entire driveline is locked, and putting it into R or D results in all 4 wheels actually spinning and no grinding sounds whatsoever. With the t-case motor unbolted, it responds to the dash switch commands by moving into any of the three positions. And using ForScan, there are no TCCM module faults. So I'm being led away from the motor as the culprit. Since I can readily move between 2wd and 4hi, I'm led away from thinking it's a vacuum issue. Any ideas out there? Every ESOF 4x4 system I've ever had has managed to crap out in one way or other but wish as I may, the levers are never coming back
FYI I have a double-post on the F150 forum
Cargo Master
Joined: Dec 2003
Posts: 2,735
Likes: 38
From: Sunny Florida
I've read where the vacuum control valve for the front hubs goes bad but that causes noise when driving. Not sure if it would cause your problem. Maybe the shift motor works when it sees less load and works when you have things apart? I know I may not be of much help.
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2nd Gear
Joined: Jun 2023
Posts: 2
Likes: 0
Thanks for the reply. I think the latter suggestion is plausible, but I would think if there is an issue with vacuum wouldn't it want to default into 4hi? I guess from my basic understanding of that system I'd think 4hi and 4lo would readily switch back and forth if vacuum was lost, but 2wd would be unavailable. But Ill admit I've never had vacuum controlling my hubs so take it with a grain of salt.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
If the vacuum to the front hubs went away it would not default to 4hi.
The front hubs would engage the front axles, but the front axles would not be powered (nor would the front hubs).
The transfer case needs to engage the front driveshaft in order to power the front axles.
The front hubs would engage the front axles, but the front axles would not be powered (nor would the front hubs).
The transfer case needs to engage the front driveshaft in order to power the front axles.
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