03 4x4 issues

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Aug 12, 2019 | 02:07 PM

Sheps78

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03 4x4 issues

I have a 2003 f150 5.4, my 4wd doesn't work at all. I have verified vacuum on both sides of the lines at the actuator and verified actuator function. Also verified that the gem module clicks and the dash lights light up when I switch on 4x4. Checked that the front driveshaft does turn when in 4x4 and moving but the front wheels don't lock in. Is there anything on these trucks I may have missed or am I looking at rebuilding the front end? Last time I got 4x4 to work it was violent howling and clunking sitting still and would not disengage unless I put it in park and shut the truck off and back on. There is no issues driving around in 2wd but I'm not extremely familiar with 4x4 systems so wanting to make sure there's nothing else it might be before I rip into it.

Aug 12, 2019 | 03:34 PM

geo6x

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From: Phoenix

Go to the first page of this 1997-2003 F-150 section and read the first Sticky. I think it will help you troubleshoot.

Aug 12, 2019 | 03:40 PM

Sheps78

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I have and everything on it checks out ok except the shift fork but it doesn't go into any detail about if there's a way to see if it's actually the problem

Aug 12, 2019 | 06:00 PM

geo6x

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This guy is good, lots of detail:

Ford uses IWE's.....others on here may be able to suggest how to troubleshoot those.

Aug 12, 2019 | 06:23 PM

steve(ill)

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There 2003 does not have IEW ( engagement at the front wheel ends)... That started in 2004 .. You have a transfer case with a motor that shifts to select 2H - 4H- 4L gearing ... When you select 4H or 4L the front driveshaft will be engaged. You can crawl under the truck ( motor off) and try to rotate the driveshaft when in 4x and it will not turn.. Shift back to 2 x and you can rotate the shaft..

After the drive shaft engages, then the vacuum piston on the PUMPKIN engages the drive shaft to the axle shaft. Two vacuum hoses.. one to ENGAGE and one to DISENGAGE.. You have to look at or check operation of the external arm on the vacuum piston to see that it is going full stroke... when the axle is ENGAGE, you can jack one tire off the ground and try to rotate ( when in 4 x) and it should not turn...it will be LOCKED to the drive shaft.... when in 2 x the wheel should rotate when off the ground.

Aug 13, 2019 | 06:55 PM

Bluegrass 7

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If you see the 4h and /or 4L light on, the system has worked>>>>up to the front axle engagement point.
The dash light being on is NOT telling you everything worked because the system cannot tell you the front axle has engaged because it's vacuum operated and has no sensors to tell you. A short coming of the system design.
The Actuator uses a Yoke to move a splined collar to connect the ends of the passenger side CV axle.
Do not tear apart the center carrier section looking for this issue when it's easy to check the operation out.
The spline function is not inside the carrier but in the housing the Actuator works at.
If all this works, the problem is likely to be in the transfer case.
Good luck..

Aug 13, 2019 | 07:14 PM

Sheps78

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Thanks guys. I did some digging and found info on the plastic ends of the shift fork that the actuator moves breaking off. I figure that's probably a more likely culprit than the front diff being jacked up. I have it narrowed down to everything working like it should but the front wheels won't lock in so whenever I get the time I'm going to pull that half shaft off and see if that fork is the problem.