First off the truck is a 99' Expedition (E.B. 5.4) and the 4wd light comes on and flashes constant until I turn it off and restart it then it does not come back on. I noticed it does it when it is cold, and when I turn the wheel like it is engaging it somehow??? After the truck warms a bit I can restart the motor and all is well but if it is cold out it just does it again. Also I notice the tires are sticking, almost like pushing sideways when I try to turn the wheel in the morning and they kind of clunk a bit causing the 4wd light to come on and flash constantly. Is this coincidence? Thanks for any input. I really hate to pay the high dollar at the dealer so anything you pro's can come up with will be greatly appreciated.

 

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Could be a bad speed sensor on the transfer case...they will cause flashing 4x4 light.

 

Could be several things.

Need to have the codes pulled. You'll need a scanner capable of pulling Ford-specific codes. Don't know if the cheapos will work, but it's worth a stop at AutoZone.

Steve

 

Autozonw cannot pull the codes for your 4WD. You definately have a sensor gone. Only Ford or a good transmission shop can pull the codes from the transfer case sensors. It sounds to me like your hall effect sensors are bad.... there are 2 of them. I hope this helps.

 

Thank you all for the info. I will get it looked at over at the ford dealer. Hopefully it will not be too expensive.

 

The 4x4 dashlight on my 99 xlt w/79000 just started flashing tonight(Sunday 8-20). It shifts into 4h and 4l just fine, but in AWD the dash light blinks... It doesn't exhibit any of the symptoms as noted in previous posts... She drives fine, and except for the wipers coming on when I open the drivers window and the rear wiper only working when it's NOT raining, she has served me well... I searched posts here at FTE and I looked in the original owners manual but to no avail... Of course, I might just be not that smart and missed them... I wish my OD light was blinking... I would have solved that an hour ago...
I also have a recall notice for a speed control deactivation switch... Possibly related???

 

Does anyone know what the ohms are supposed to be on transfer case sensors? would like to test before buying,also the relay switches as well in the dash what they should read ? I've been trying to locate the transmission sensor but to no avail ( I must be blind) is it on this truck? already tested sensor on rear diff. thanks to info here thats fine 4x4 lights flashing got codes P1837 (transfer case sensor ) and C1107 this is on a 1999 navigator 4x4 5.4 any insite on this would be appreciated ,It feels like its 4wd until I get to 30mph then 4x4 light starts flashing I did just have a wheel bearing replaced on front drivers side but flashing was there before that and odometer is flashing but I think I seen the fix for that I have not done the odometer thing yet Thanks (This site has tons of info so glad I found it !