Problem with 4wd
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Freshman User
Joined: Nov 2010
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Problem with 4wd
I recently got a 02 F-350 auto with a 7.3. I just found out the 4wd is not engaging. I read a few threads about locking the hubs and checking if the front drive shaft will spin. I also haven't checked any fuses. My question is should there be any 4wd light on the dash? There are no lights that come on when I switch it into 4wd.
Thanks for the help
Thanks for the help
Cargo Master
Joined: Jun 2003
Posts: 3,292
Likes: 6
From: Ardenvoir, Washington
Yes, there should be a light indicating that you are in 4wd, either high or low.. Check the fuses first.. If you have a ohm meter, you can check the fuses without pulling them out of the box.. just put the leads on the exposed openings on the top of the fuse for a continuity check..
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http://i74.photobucket.com/albums/i2...mx/Picture.jpg
I attached the wiring diagram i am using from the EVTM. I hope you can see it because it is kind of small.
I checked for pwr at the rd/lg wire at the connector on the 4wd control module and I have power there. Then I checked for power at the 4wd switch at the wh/lb wire and I have no power. Then I checked for continuity from the wh/lb wire from the switch to the connector at the module and I have continuity, so I know it is not a broken wire.
Does this look like I have a bad control module? Also all the tests were done with the key on not running if that matters.
Thanks
I attached the wiring diagram i am using from the EVTM. I hope you can see it because it is kind of small.
I checked for pwr at the rd/lg wire at the connector on the 4wd control module and I have power there. Then I checked for power at the 4wd switch at the wh/lb wire and I have no power. Then I checked for continuity from the wh/lb wire from the switch to the connector at the module and I have continuity, so I know it is not a broken wire.
Does this look like I have a bad control module? Also all the tests were done with the key on not running if that matters.
Thanks
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Freshman User
Joined: Nov 2010
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I was able to find someone who had a module that I could plug in so I tried it and it didnt work. I was reading the evtm wrong. The 4wd switch is a ground side switch like most switches and there should not have been power there anyway, oops.
Some how the 4WD engaged but now it wont disengage. This thing is killing me. So anyway that means the hubs are locked even though they are in the auto position and the transfer case is stuck on 4WD
My two questions are I removed the Vacuum lines from the hub to see if they would dis engage but nothing, how can they be locked in the auto position with no vacuum?
Also I took the transfer case motor off to see if it was gummed up. I tried the move the selector on the transfer case by hand but it wouldn't move, should it?
Thanks and sry for the huge post.
Some how the 4WD engaged but now it wont disengage. This thing is killing me. So anyway that means the hubs are locked even though they are in the auto position and the transfer case is stuck on 4WD
My two questions are I removed the Vacuum lines from the hub to see if they would dis engage but nothing, how can they be locked in the auto position with no vacuum?
Also I took the transfer case motor off to see if it was gummed up. I tried the move the selector on the transfer case by hand but it wouldn't move, should it?
Thanks and sry for the huge post.
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Freshman User
Joined: Nov 2010
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I tried replacing the t-case motor because I had power to it. It still does not function.
My buddy has a F-250 with a 5.4 and I noticed that he has a floor shifter for 4wd. Does anyone know if I got the linkage and shifter from a junkyard if I could use that instead of the electric motor? I wasn't sure if they were the same t-cases.
My buddy has a F-250 with a 5.4 and I noticed that he has a floor shifter for 4wd. Does anyone know if I got the linkage and shifter from a junkyard if I could use that instead of the electric motor? I wasn't sure if they were the same t-cases.
Tuned
Joined: Feb 2010
Posts: 402
Likes: 2
From: Colorado Springs
I was able to find someone who had a module that I could plug in so I tried it and it didnt work. I was reading the evtm wrong. The 4wd switch is a ground side switch like most switches and there should not have been power there anyway, oops.
Some how the 4WD engaged but now it wont disengage. This thing is killing me. So anyway that means the hubs are locked even though they are in the auto position and the transfer case is stuck on 4WD
My two questions are I removed the Vacuum lines from the hub to see if they would dis engage but nothing, how can they be locked in the auto position with no vacuum?
Also I took the transfer case motor off to see if it was gummed up. I tried the move the selector on the transfer case by hand but it wouldn't move, should it?
Thanks and sry for the huge post.
Some how the 4WD engaged but now it wont disengage. This thing is killing me. So anyway that means the hubs are locked even though they are in the auto position and the transfer case is stuck on 4WD
My two questions are I removed the Vacuum lines from the hub to see if they would dis engage but nothing, how can they be locked in the auto position with no vacuum?
Also I took the transfer case motor off to see if it was gummed up. I tried the move the selector on the transfer case by hand but it wouldn't move, should it?
Thanks and sry for the huge post.
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Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Just removing the vacuum lines won't dis-engage 4WD. The auto hub locks are a "latching" system. The system uses different-level vacuum "pulses" to latch and un-latch. Suck-pulse to lock, suck-pulse again to unlock.
Inside the hub locks is a little mechanism that kinda' reminds me of the action at the end of a common ball-point-pen.
I forget the specific vacuum values or I would include them here.
Since the locks are identical from side-to-side, "front of truck" and "back of truck" is only applicable on one side. The other side will be the reverse.
Better to remember that clockwise is Manual-locked, counter-clockwise is Auto-locking. The hub locks can only be free in the Auto position.
Pop
Inside the hub locks is a little mechanism that kinda' reminds me of the action at the end of a common ball-point-pen.
I forget the specific vacuum values or I would include them here.
Better to remember that clockwise is Manual-locked, counter-clockwise is Auto-locking. The hub locks can only be free in the Auto position.
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Joined: Jun 2010
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From: The great North East.
When I purchased my 02 it also would not lock into 4WD. Then suddenly it did once but then I could not get it back out. I crawled underneath and manualy shifted the motor with a wrench to get it out. The next weekend I removed the old oil from the transfer case and then added the correct Motorcraft synthetic oil.
Once I had the fluid changed, I manually moved the shift motor back and forth, many, many, many times! After 15 or so minutes I could start to feel it shift easier, so I kept going. After shifting it back and forth many more times, the motor started to shift rather easily.
Now when I shift the truck into 4WD it works flawlessly.
Hope this helps!
Once I had the fluid changed, I manually moved the shift motor back and forth, many, many, many times! After 15 or so minutes I could start to feel it shift easier, so I kept going. After shifting it back and forth many more times, the motor started to shift rather easily.
Now when I shift the truck into 4WD it works flawlessly.
Hope this helps!
Lead Driver
Joined: Dec 2006
Posts: 7,093
Likes: 147
From: San Diego, CA
IIRC the locking pulse is around 10" and the unlock is around 6". The pulse should last around 30 seconds or so but it only takes a few seconds above the required vacuum to actuate the lock or unlock (or click the ball point pen as SpringerPop mentioned).
The hubs and t-case are independent operations common to the selector **** on the dash. A problem with one does not indicate a problem with the other. Unless there's a selector switch problem you could be chasing more than one gremlin.
It is recommended to engage (and drive in) 4wd at least once a month for several miles (in the dirt obviously) to ensure proper lubrication and operation of the entire system. I had hub problems when I bought my truck and one of mine was frozen in the unlocked position. There's a way to clean your locking hubs by going to:
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
As for the electronic side with the t-case, I've not had that problem. There's plenty of stuff to search on for 4wd issues, though, as lots of us have had problems with it.
Best of luck!
The hubs and t-case are independent operations common to the selector **** on the dash. A problem with one does not indicate a problem with the other. Unless there's a selector switch problem you could be chasing more than one gremlin.
It is recommended to engage (and drive in) 4wd at least once a month for several miles (in the dirt obviously) to ensure proper lubrication and operation of the entire system. I had hub problems when I bought my truck and one of mine was frozen in the unlocked position. There's a way to clean your locking hubs by going to:
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
As for the electronic side with the t-case, I've not had that problem. There's plenty of stuff to search on for 4wd issues, though, as lots of us have had problems with it.
Best of luck!
Lead Driver
Joined: Dec 2006
Posts: 7,093
Likes: 147
From: San Diego, CA
IIRC the transfer case in my '03 requires about 4 qts of ATF. I would recommend checking your owner's manual before changing any fluid to make sure you get the correct stuff in there.
Thread Starter
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Freshman User
Joined: Nov 2010
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IIRC the locking pulse is around 10" and the unlock is around 6". The pulse should last around 30 seconds or so but it only takes a few seconds above the required vacuum to actuate the lock or unlock (or click the ball point pen as SpringerPop mentioned).
The hubs and t-case are independent operations common to the selector **** on the dash. A problem with one does not indicate a problem with the other. Unless there's a selector switch problem you could be chasing more than one gremlin.
It is recommended to engage (and drive in) 4wd at least once a month for several miles (in the dirt obviously) to ensure proper lubrication and operation of the entire system. I had hub problems when I bought my truck and one of mine was frozen in the unlocked position. There's a way to clean your locking hubs by going to:
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
As for the electronic side with the t-case, I've not had that problem. There's plenty of stuff to search on for 4wd issues, though, as lots of us have had problems with it.
Best of luck!
The hubs and t-case are independent operations common to the selector **** on the dash. A problem with one does not indicate a problem with the other. Unless there's a selector switch problem you could be chasing more than one gremlin.
It is recommended to engage (and drive in) 4wd at least once a month for several miles (in the dirt obviously) to ensure proper lubrication and operation of the entire system. I had hub problems when I bought my truck and one of mine was frozen in the unlocked position. There's a way to clean your locking hubs by going to:
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
As for the electronic side with the t-case, I've not had that problem. There's plenty of stuff to search on for 4wd issues, though, as lots of us have had problems with it.
Best of luck!
When I got the new t-case motor I connected both connectors to it and had my dad turn the selector *** and nothing moved. Then I had him ground the OR/LB wire at the 4wd relay with a test light (which the 4wd module is suppose to supply the ground) and the motor moved to 4wd.
So either there is a broken wire somewhere from the 4wd module, the switch is bad, or the module is bad. I will keep the thread updated if I find the issue.
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Freshman User
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I have not bench tested them. But with the relay still plugged in I turned it over and touched the OR/LB wire with a test light basically supplying the relay the ground its suppose to get from the module, and I feel it click and the transfer case motor moves positions.
So I need to find out if the module is not sending ground because it is bad or it is not seeing correct input from the switch.
I tried testing the 4wd selector switch to see if any position had an open but each position had a different resistance which its suppose to but its possible that it could be the wrong resistance seeing how I dont know what range of resistance for each position.
The next thing I want to check is to see if the WH/LB wire at the switch (which is reference voltage) is getting the 6V the it is suppose to.
So I need to find out if the module is not sending ground because it is bad or it is not seeing correct input from the switch.
I tried testing the 4wd selector switch to see if any position had an open but each position had a different resistance which its suppose to but its possible that it could be the wrong resistance seeing how I dont know what range of resistance for each position.
The next thing I want to check is to see if the WH/LB wire at the switch (which is reference voltage) is getting the 6V the it is suppose to.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
Just an FYI:
This is the type of relay for both ESOF relays.
There should be continuity between terminal 87a and terminal
30 through break contact 87a with relay non-operated.
Easy check with VOM when relays are pulled.
This is the type of relay for both ESOF relays.
There should be continuity between terminal 87a and terminal
30 through break contact 87a with relay non-operated.
Easy check with VOM when relays are pulled.