4wd shifts after starting, not after driving.

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Old 12-25-2017, 11:07 AM
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4wd shifts after starting, not after driving.

Haven't seen this listed yet, suspecting electrical?
2003 F150, floor shift 4x4, 117,000 K, all original. (no lifts, chips, pipes etc)
If I start the truck, move around the yard, 4wd works fine. Drove 15 minutes to town, washed truck, ran errands, 4wd would not work when got home. Put truck in 'heated' shop (un-unsulated, torpedo heater running) hoping it was moisture somewhere. Tried couple hours later, worked great, drove up and down road, no 4X4. Light goes of and on as expected, clicking can heard from dash/firewall when shifting. I shut off the truck, depleted vacuum by changing heater selections (just fixed that too, mice under dash chewed vacuum line). Re-started truck, 4x4 engaged and stayed engaged. Have read many forums on 4x4 not shifting, have not seen this same scenario.
when it works, it works great, pulls strong. When it doesn't, there is no clicking, no partial engagement. Rocking forwards and back, sitting, driving around yard no change.

Am I right in thinking I should be checking/changing the 2 solenoids on firewall? Suspecting a sticky release on the 2wd to release vacuum on hubs to allow hubs to lock. With lever in 4Hi, front drive shaft appears engaged to rear shaft (rocking by hand). Hubs were replaced 5ish years, not many miles ago. Truck is semi retired to being a farm truck, and I use it all winter for contract work.

​​​​​​​any ideas would be much appreciated.
 
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Old 12-25-2017, 04:11 PM
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The 2003 doesn't have vacuum hubs, it has a differential lock.
 
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Old 01-02-2018, 06:03 PM
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Originally Posted by black sheep
Haven't seen this listed yet, suspecting electrical?
2003 F150, floor shift 4x4, 117,000 K, all original. (no lifts, chips, pipes etc)
If I start the truck, move around the yard, 4wd works fine. Drove 15 minutes to town, washed truck, ran errands, 4wd would not work when got home. Put truck in 'heated' shop (un-unsulated, torpedo heater running) hoping it was moisture somewhere. Tried couple hours later, worked great, drove up and down road, no 4X4. Light goes of and on as expected, clicking can heard from dash/firewall when shifting. I shut off the truck, depleted vacuum by changing heater selections (just fixed that too, mice under dash chewed vacuum line). Re-started truck, 4x4 engaged and stayed engaged. Have read many forums on 4x4 not shifting, have not seen this same scenario.
when it works, it works great, pulls strong. When it doesn't, there is no clicking, no partial engagement. Rocking forwards and back, sitting, driving around yard no change.

Am I right in thinking I should be checking/changing the 2 solenoids on firewall? Suspecting a sticky release on the 2wd to release vacuum on hubs to allow hubs to lock. With lever in 4Hi, front drive shaft appears engaged to rear shaft (rocking by hand). Hubs were replaced 5ish years, not many miles ago. Truck is semi retired to being a farm truck, and I use it all winter for contract work.

any ideas would be much appreciated.
​​​​​​​Check that clicker box mine had solder cracked and was an easy fix.
 



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