Truck won’t go over 28Mph
#1
12-14-2017, 11:46 PM
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Truck won’t go over 28Mph
So last night I was driving slow and I was hitting patches of ice so I tried switching my truck into 4WD and there was a loud clank noise and the speedometer went all the way up to 80. Trying to drive home the speedometer was showing I was doing 60 when I was only doing probably 20 and there was a humming noise. Today it came out of 4WD but will no longer engage, Also the engine RPMs are as high as they would be if the truck were actually doing 60mph when I was doing 28mph. I need some ideas on what it could be please 1999 F-150 Automatic
Last edited by Steven Baker; 12-14-2017 at 11:50 PM.
#2
12-15-2017, 02:12 AM
My suspicion is the Gem went into 4L for some reason.
Normally you have to stop, put trans in Neutral with foot on brake before the system will go into 4l.
4L has no sync like 4H and will crunch and grind so is not normally allowed to engage unless the truck s stopped per the above..
If the Gem has been wet from a leaking windshield, anything can happen anytime moving or not.
4L causes a shift sked change signaled by the transfer case motor running to second position so the motor won't run excessive high rpm in each gear before auto shifting.
Otherwise the 4wd has no connection to the speedometer. It's driven from the computer.
Good luck.
Normally you have to stop, put trans in Neutral with foot on brake before the system will go into 4l.
4L has no sync like 4H and will crunch and grind so is not normally allowed to engage unless the truck s stopped per the above..
If the Gem has been wet from a leaking windshield, anything can happen anytime moving or not.
4L causes a shift sked change signaled by the transfer case motor running to second position so the motor won't run excessive high rpm in each gear before auto shifting.
Otherwise the 4wd has no connection to the speedometer. It's driven from the computer.
Good luck.
#3
12-15-2017, 10:51 PM
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