4wd light
Question:
Hi, Have a 1997 Ford Explorer AWD that just started having the 4wd and 4wd low lights come on (flash). Seems fine in 2whl drive, but won’t go into 4wd when done manually. Got a code 1781. Any ideas what might be going on, what to check. J. London
Response:
That flashing is a signal from the GEM computer that indicates a problem in the Control-Trac system. Typically it is one of the axle speed sensors that has failed. In the auto position on your model the system monitors relative front and rear axle speeds, increasing the period of engagement of the clutch pack in the transfer case to eliminate the rear moving faster than the front. If it gets to full-lock, for example, and the rear still seems to be turning faster then it reverts the system to 2WD in the default, auto position. Some have reported cleaning the contacts on the speed sensors has helped, but you may want to get to a dealer if the problem persists. Watch that they don’t automatically try to replace the computer or the transfer case. Ususally it is just a sensor problem. Good Luck. =Vic= Bear Gap, PA – Hide quoted text — Show quoted text – > Hi, > Have a 1997 Ford Explorer AWD that just started having the 4wd and 4wd low > lights come on (flash). Seems fine in 2whl drive, but won’t go into 4wd > when done manually. Got a code 1781. Any ideas what might be going on, > what to check. > J. London
Response:
Had the lights blinkin, and at slow speed in 4WD Auto I could hear a binding noise that led me to believe the transfer case was being told to turn the front axle at more/less speed than it should have. When I made a sharp turn at 5 MPH, I slowed down REAL fast because of this "binding". The light would never illuminate, just wait until it started blinking, although I could feel it engaged. 4WD Low would work just fine. I cleaned the front wheel sensor c onnectors in the wheel wells, and that took care of the problem. Lots of dust and dirt in there. I could feel the sand in the plastic connector as I disconnected the two ends, real gritty. -IanCT
– Hide quoted text — Show quoted text -> That flashing is a signal from the GEM computer that indicates a problem > in the Control-Trac system. Typically it is one of the axle speed > sensors that has failed. In the auto position on your model the system > monitors relative front and rear axle speeds, increasing the period of > engagement of the clutch pack in the transfer case to eliminate the rear > moving faster than the front. If it gets to full-lock, for example, and > the rear still seems to be turning faster then it reverts the system to > 2WD in the default, auto position. Some have reported cleaning the > contacts on the speed sensors has helped, but you may want to get to a > dealer if the problem persists. Watch that they don’t automatically try > to replace the computer or the transfer case. Ususally it is just a > sensor problem. > Good Luck. > =Vic= > Bear Gap, PA > Hi, > Have a 1997 Ford Explorer AWD that just started having the 4wd and 4wd low > lights come on (flash). Seems fine in 2whl drive, but won’t go into 4wd > when done manually. Got a code 1781. Any ideas what might be going on, > what to check. > J. London
Response:
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