HELP
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Junior User
Joined: Apr 2013
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From: CORPUS CHRISTI TX
HELP
I have a 2003 f250 4wd and I just replaced the hub assembly and the dust seal on my front axle, I put it all back together and drove it and ran perfectly fine, then I get to the beach lock my hubs and put it in 4low and 4wd works perfect, then I make it back to hard ground turn it back to 2wd unlock my hubs and my 4wd light on my dash and low range light don't come off and my truck sounds like it don't want to shift and had high rpm??????
Hotshot
Joined: Apr 2010
Posts: 19,072
Likes: 242
From: Saratoga Springs,UT
4 low Has a Very Specific order of events that must take place to shift In or Out of 4Low maybe you did them IDK but lets Go over the Sequence of events
For a Shift Attempt From 2H to 4H or 4L, the Following Sequence Occurs:
MSS is switched from 2H to 4H or 4L
For shift attempts into 4L:
the brake must be applied.
transmission must be in NEUTRAL (or clutch pedal applied).
vehicle speed must be below 8 km/h (5 mph).
Shift motor moves range fork in transfer case, which engages dual-cone synchronizers
If a blocked shift condition occurs, the shift motor will perform 10 shift attempts (2H to 4H or 4H to 4L) totaling 5 clockwise
movements and 5 counterclockwise movements with an approximate 1-second delay between each motor movement attempt
If, after 10 attempts, a shift is not completed, then the module will command a shift motor rest time of 40 seconds, before it
attempts any further shifts
After the 40 seconds have expired, the motor will make 10 more attempts to complete the shift. The motor will continue to
repeat this sequence a total of 6 times (60 shift attempts) before ceasing operation. No further shift attempts will be made,
nor will any further MSS commands be recognized. The vehicle must be restarted for 4x4 function to be restored. If this
occurs, DTC C1728 (for 2H to 4H attempts) or DTC C1729 (for 4H to 4L shift attempts) will be stored in memory
If the vehicle is driven above 5 km/h (3 mph) during a 40-second rest period, the module will reattempt the shift strategy
outlined previously. Generally, the transfer case will engage as the probability of gear teeth blockage is greatly reduced
while rolling
If no gear teeth blockage is present, the transfer case synchronizers bring the front driveshaft to same speed as rear
driveshaft
Shift fork completes movement and the "4x4" and (if 4L) "Low Range" lamp will illuminate. This ONLY occurs when the
driveshafts are synchronized. If they are not, then the "4x4" lamp will not illuminate
Once the 4x4 lamp is illuminated, the PVH lock and lock/unlock solenoids are energized for 45 seconds, with approximately
62 kPa (9 psi) of vacuum or more at the hubs. The PVH lock sequence cannot be overridden at any time (a mode shift
change back to 2H)
After 45 seconds have elapsed, the solenoids undergo a 6-second vent period, whereby no commands to either the lock or
lock/unlock solenoids are allowed, regardless of MSS position
If the vehicle is driven above 8 km/h (5 mph) the PVH lock and lock/unlock solenoids are re-energized in the same manner,
regardless of whether the hubs are engaged or the original 45-second engagement timer has expired
For a Shift Attempt from 4L to 4H to 2H, the Following Sequence Occurs:
4x4 mode select switch is placed from 4H or 4L to 2H
For shift attempts out of 4L:
the brake must be applied.
transmission must be in NEUTRAL (or clutch pedal applied).
vehicle speed must be below 8 km/h (5 mph).
Shift motor moves range fork in transfer case, which disengages dual-cone synchronizers
If a blocked shift condition occurs, the shift motor will perform 10 shift attempts from 4H or 4L to 2H to 4H or 4L to 2H totaling
5 clockwise movements and 5 counterclockwise movements with an approximate 1-second delay between each motor
movement attempt
If, after 10 attempts, a shift is not completed, then the module will command a shift motor rest time of 40 seconds, before it
attempts any further shifts
After the 40 seconds have expired, the motor will make 10 more attempts to complete the shift. The motor will continue to
repeat this sequence a total of 6 times (60 shift attempts) before ceasing operation. No further shift attempts will be made,
nor will any further MSS commands be recognized. The vehicle must be restarted for 4x4 function to be restored. If this
occurs, DTC C1728 (for attempts between 2H and 4H) or DTC C1729 (for attempts between 4H and 4L) will be stored in
memory.
If the vehicle is driven above 3 mph (5 km/h) during a 40-second rest period, the module will reattempt a shift (4H to 2H
only). Generally, the transfer case will disengage as the probability of torque trapping is lower while rolling
If no torque trapping is present, the transfer case synchronizers decouple the front driveshaft
Shift fork completes movement and de-energizes "4x4", and if 4L, "Low Range" lamps. Once the 4x4 lamp is de-energized,
the PVH lock/unlock solenoid is energized for 15 seconds, pulling approximately 41 kPa (6 psi) of vacuum at the hubs
The PVH unlock sequence can be overridden at any time such as a mode shift change back to 4H or 4L, relocking the hubs
After 15 seconds, the solenoids undergo a 6-second vent period; the vent period can be overridden at any time by a shift
attempt to 4H or 4L.
For a Shift Attempt From 2H to 4H or 4L, the Following Sequence Occurs:
MSS is switched from 2H to 4H or 4L
For shift attempts into 4L:
the brake must be applied.
transmission must be in NEUTRAL (or clutch pedal applied).
vehicle speed must be below 8 km/h (5 mph).
Shift motor moves range fork in transfer case, which engages dual-cone synchronizers
If a blocked shift condition occurs, the shift motor will perform 10 shift attempts (2H to 4H or 4H to 4L) totaling 5 clockwise
movements and 5 counterclockwise movements with an approximate 1-second delay between each motor movement attempt
If, after 10 attempts, a shift is not completed, then the module will command a shift motor rest time of 40 seconds, before it
attempts any further shifts
After the 40 seconds have expired, the motor will make 10 more attempts to complete the shift. The motor will continue to
repeat this sequence a total of 6 times (60 shift attempts) before ceasing operation. No further shift attempts will be made,
nor will any further MSS commands be recognized. The vehicle must be restarted for 4x4 function to be restored. If this
occurs, DTC C1728 (for 2H to 4H attempts) or DTC C1729 (for 4H to 4L shift attempts) will be stored in memory
If the vehicle is driven above 5 km/h (3 mph) during a 40-second rest period, the module will reattempt the shift strategy
outlined previously. Generally, the transfer case will engage as the probability of gear teeth blockage is greatly reduced
while rolling
If no gear teeth blockage is present, the transfer case synchronizers bring the front driveshaft to same speed as rear
driveshaft
Shift fork completes movement and the "4x4" and (if 4L) "Low Range" lamp will illuminate. This ONLY occurs when the
driveshafts are synchronized. If they are not, then the "4x4" lamp will not illuminate
Once the 4x4 lamp is illuminated, the PVH lock and lock/unlock solenoids are energized for 45 seconds, with approximately
62 kPa (9 psi) of vacuum or more at the hubs. The PVH lock sequence cannot be overridden at any time (a mode shift
change back to 2H)
After 45 seconds have elapsed, the solenoids undergo a 6-second vent period, whereby no commands to either the lock or
lock/unlock solenoids are allowed, regardless of MSS position
If the vehicle is driven above 8 km/h (5 mph) the PVH lock and lock/unlock solenoids are re-energized in the same manner,
regardless of whether the hubs are engaged or the original 45-second engagement timer has expired
For a Shift Attempt from 4L to 4H to 2H, the Following Sequence Occurs:
4x4 mode select switch is placed from 4H or 4L to 2H
For shift attempts out of 4L:
the brake must be applied.
transmission must be in NEUTRAL (or clutch pedal applied).
vehicle speed must be below 8 km/h (5 mph).
Shift motor moves range fork in transfer case, which disengages dual-cone synchronizers
If a blocked shift condition occurs, the shift motor will perform 10 shift attempts from 4H or 4L to 2H to 4H or 4L to 2H totaling
5 clockwise movements and 5 counterclockwise movements with an approximate 1-second delay between each motor
movement attempt
If, after 10 attempts, a shift is not completed, then the module will command a shift motor rest time of 40 seconds, before it
attempts any further shifts
After the 40 seconds have expired, the motor will make 10 more attempts to complete the shift. The motor will continue to
repeat this sequence a total of 6 times (60 shift attempts) before ceasing operation. No further shift attempts will be made,
nor will any further MSS commands be recognized. The vehicle must be restarted for 4x4 function to be restored. If this
occurs, DTC C1728 (for attempts between 2H and 4H) or DTC C1729 (for attempts between 4H and 4L) will be stored in
memory.
If the vehicle is driven above 3 mph (5 km/h) during a 40-second rest period, the module will reattempt a shift (4H to 2H
only). Generally, the transfer case will disengage as the probability of torque trapping is lower while rolling
If no torque trapping is present, the transfer case synchronizers decouple the front driveshaft
Shift fork completes movement and de-energizes "4x4", and if 4L, "Low Range" lamps. Once the 4x4 lamp is de-energized,
the PVH lock/unlock solenoid is energized for 15 seconds, pulling approximately 41 kPa (6 psi) of vacuum at the hubs
The PVH unlock sequence can be overridden at any time such as a mode shift change back to 4H or 4L, relocking the hubs
After 15 seconds, the solenoids undergo a 6-second vent period; the vent period can be overridden at any time by a shift
attempt to 4H or 4L.
Lead Driver
Joined: Jul 2004
Posts: 6,951
Likes: 512
From: Foothills, CA
I've had mine bind up like this on pavement. I'd try it again in the dirt and if all else fails I've had luck rolling the truck slowly (under 5mph) and putting in neutral turning switch and softly applying brakes, so that truck keeps rolling just a bit.
You do have shift on the fly and not a manual transfer case, right? Auto/manual hubs or manual only?
You do have shift on the fly and not a manual transfer case, right? Auto/manual hubs or manual only?
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Junior User
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From: CORPUS CHRISTI TX
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