02 f150 4x4 problem
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02 f150 4x4 problem
I have a 02 f150 4x4 with shift on the fly. It will go in 4x4 sometimes after I hear it clicking a few times in the dash but sometimes I have to keep turning the switch from 2 to 4 a few times. but it want go in 4x4 low at all. and it want go back in 4x2 unless I turn truck off and turn the switch. then it will go in 4x2 when I restart it.
Lead Driver
Joined: Sep 2006
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If you see it attempts to engage the transfer case, my vote is the case motor is not working reliably.
The clicking you hear is the GEM module operating the relay trying to get the case motor to it's fist position.
It has to get there in order to operate the firewall solenoid to transfer engine vacuum to the front actuator so front axle locks together. At this point the dash light come on. If it does not, the case motor did not operate.
Only difference in 4L is the case motor runs one more position, engages the gear reduction in the transfer case, and changes the engine shift skeduial plus 4L light comes on.
Carefully see what it does and decide what is happening or not happening before changing any parts.
The clicking you hear is the GEM module operating the relay trying to get the case motor to it's fist position.
It has to get there in order to operate the firewall solenoid to transfer engine vacuum to the front actuator so front axle locks together. At this point the dash light come on. If it does not, the case motor did not operate.
Only difference in 4L is the case motor runs one more position, engages the gear reduction in the transfer case, and changes the engine shift skeduial plus 4L light comes on.
Carefully see what it does and decide what is happening or not happening before changing any parts.
Hotshot
Joined: Jan 2004
Posts: 19,762
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From: St Louis
Stop trying to shift on the fly. Stop the truck and shift between 2 x 4 and 4 x 4 HI.
Lead Driver
Joined: Sep 2006
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ESOF is accomplished with a feature incorporated into the transfer case.
It is an electric operated gear sync function that allows the gear train to engage without grinding.
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Shifting to 4L does require the truck to be at rest, in neutral and foot on brake. The GEM is in control of this requirement, by movement detection, operated brake pedal and neutral selection all have to be present at the same time to access 4L..
Obvious why; you do not want to engage such a low gear ratio at speed.
It bangs heads, breaks windshields, hard on drive train etc., besides changing the engine shifting rpm.
You do not want these things going on at highway speeds.
It is an electric operated gear sync function that allows the gear train to engage without grinding.
.
Shifting to 4L does require the truck to be at rest, in neutral and foot on brake. The GEM is in control of this requirement, by movement detection, operated brake pedal and neutral selection all have to be present at the same time to access 4L..
Obvious why; you do not want to engage such a low gear ratio at speed.
It bangs heads, breaks windshields, hard on drive train etc., besides changing the engine shifting rpm.
You do not want these things going on at highway speeds.
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I'm not trying it while moving, I'm sitting in my driveway. dont care if the 4x4low work just trying to get it in an out of 4x4 hi. I can get it to go in 4x4 hi sometimes but sometimes I have to turn the switch a few times. but only way to get it back in 4x2 is to turn ignition off and restart it and it resets itself to 4x2.
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Fleet Owner
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I'm not trying it while moving, I'm sitting in my driveway. dont care if the 4x4low work just trying to get it in an out of 4x4 hi. I can get it to go in 4x4 hi sometimes but sometimes I have to turn the switch a few times. but only way to get it back in 4x2 is to turn ignition off and restart it and it resets itself to 4x2.
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I just drove it again and if I switch to 4x4 hi while moving it starts squealing underneath and when I almost stop it pops like it engaged to 4x4. if I check the the voltage on the 2 relays next to the battery after I switch the switch to 4x2 both have power, even after I turn it back to 4x4. but if I turn truck off put in 4x2 restart it only the 4x2 has power .if I then switch to 4x4 only 4x4 has power. but if I try to go back to 4x2 both has power.
Laughing Gas
Joined: Jan 2006
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From: Minnesota
Anytime I had-have an engagement issue with like "grinding" it's been one of those solenoids behind the battery. The fork moved easily, but not enough vacuum I guess to yank her in tight????? As far as 4x4 low......If I am not dead stopped, foot on the brake, in neutral, she will grind and not go. No slow roll in for my girl....LOL.
Lead Driver
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Review this 4wd operation.
The case motor rotates one position going to 4H to engage the case and do electric syncing.
It moves to a second position to engage the gear reduction for 4L.
At this position a dedicated lead to the PCM is the signal to change the RPM shift points in the program for the low gearing.
This is accomplished from a circuit board with rotary wiper contacts mounted with. the case motor.
.
My feeling is you may still have the original problem.
It was not solved by just working on the dash switch unless it was just a wire/plugup issue.
.
The case motor rotates one position going to 4H to engage the case and do electric syncing.
It moves to a second position to engage the gear reduction for 4L.
At this position a dedicated lead to the PCM is the signal to change the RPM shift points in the program for the low gearing.
This is accomplished from a circuit board with rotary wiper contacts mounted with. the case motor.
.
My feeling is you may still have the original problem.
It was not solved by just working on the dash switch unless it was just a wire/plugup issue.
.
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