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2001 ford f150 stuck in 4 lo
hello I am new to the forum and have been reading most of the day trying to figure out my issue before making a post .
Little background on the issue . I got the truck about 5 months ago and the 4wd worked the 1st day I tried it . well I figured the next day I would drive it back on a strip job road and test the 4wd out . to my surprise it would not work . I pulled the transfer case shift motor off the truck and applied power to it using a battery charger and it was like it was locked up note I had just just it the day before and it worked. I just heard clicking coming from my dash when I tried to engage the 4wd. now I ordered a new transfer case shift motor dormon brand and installed it today and got in started the truck and put it in neutral and flipped the switch heard the clicking for a brief moment and that was it next thing I know trucks in 4x4 lo. I tried getting it out of 4 lo by switching to 4 hi and then to 2wd it made no difference and no clicking when hitting the switch . any suggestions would be appricated. I checked all fuses in the cab and under the hood visually by pulling each and everyone of them out and for good measures i checked them with a test light and all seem to be getting power. Cruise control works windows roll up and down and nothing out of the ordinary with headlights signal lights etc so I don't think it could be the gcm as I read a lot think it could be. I tried turning my key off and back on and hitting the switch again as well as taking the battery terminal off and no clicking sound period anymore I read it should make 1 click to verify before it engages then the lights show on the dash . question is where are the relays for the 4wd inside the dash ? I found like a dual block that had 2 relays in it one of the 2 controlled the blinkers. The other I'm not too sure about I switched it with another one just to see and the one I pulled worked great to begin with . I did read that they are located on the passenger side but haven't gotten a chance to look yet. I'm just stomped on what to do from here . I apologize for the long post. What I mean about the relay left to right i mean the possible relays in the dash |
Do your brake lights work? It won't shift in or out of 4lo unless your foot is on the brake and the transmission is in Neutral.
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Originally Posted by glc
(Post 5241195)
Do your brake lights work? It won't shift in or out of 4lo unless your foot is on the brake and the transmission is in Neutral.
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Lets start by seeing how 4wd works.
Then you can better recognize where the fault might be. 101. Switch to 4H is a request signal to the GEM module to run the case motor to it's 'first' position (4h). This can be done while moving on the road. An electric clutch enables this to take place while moving to eliminate gear grinding. At this point a circuit is completed to one firewall solenoid to allow vacuum to operate the front axle lock up. In 4L, the case motor runs to a 'second' position. The truck must be stopped, foot on brake and shifter in neutral. This 4L position connects a signal to the computer to change the shift RPM schedule. This all has to be done because of the huge change in gearing that takes place. Both 4H and 4L cause the Gem to light the respective lamps on the dash. Trouble shooting: If the system is stuck in 4L, the case motor is in the 'second' position, has the gearing engaged and shift sked changed and the front engagement does not change from 4H . Problem is the case motor will not 'reverse' direction.. For that to happen the power to it has to be reversed in voltage polarity through the second relay. This 2 relay module is located in the center portion of the dash. If you need one, they are hard to find anywhere but a yard. What to do? Remove the case motor, see the 'shaft' it operates and turn it back to 2H.. Turn the motor back to match. This will remove front lock up by routing engine vacuum to the disconnect side of the Actuator by the second firewall solenoid. These solenoids are behind the battery area with vacuum and electrical connector lattached. Re mount the motor and leave it until you have a decision on trouble shooting or you will get into it all over again.. Good luck. |
good info bluegrass . where is exactly the 2 relays at the middle ? Towards the top or bottom ?
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Thanks bluegrass for the info . when you say the. 2 relays are in the middle area are they up high around where the radio is or down low somewhere ? I found a little black box that had 2 relays in it one was blue and the other was black . when I turned my blinker on I felt the one click the whole time the blinker was on the one beside it not sure what it goes to but I swapped it out with the fuel pump one just to make sure it worked and it did . I'm assuming the 2 relays you are talking about would be side by side as well. The ones I found where closer to the steering colum area.
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ive been out working on the truck today and the two relays I found where actually close to the middle of the truck. I did confirm I have brake lights . I also checked all fuses related to the 4x4 again just to make sure . their is no power at the transfer case motor or switch when flipping it. And I don't understand why the relay was clicking for a brief moment yesterday as it applied it into 4wd lo then it wouldn't click anymore. Called a ford tech and he suggest unhooking the battery terminals and holding them together for 20 sec . I left it unhooked for 10 mins for good measures and no change. I have no idea where to go from here on the situation but can't afford to take it to a garage to have them fix it garages around me are ridiculous on labor charges and they wanna keep one for about 3 weeks to a month. This is my daily driver so I can't do that anyways. Thanks for all help
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You found the relay module in the top center area.
Removing the battery does not do anything to this circuit. It has no memory to reset. There is no function that needs memory. The original clicks you heard was the relay operate attempt by the GEM to retry the operation a second or third time then stops. A normal action when the circuit has a fault. >>>>>>>>>>The GEM monitors the current flow to detect if operation occurs<<<<<<<<<<< There are two relays in the housing. Power to the case motor is not coming through the relay and harness.. Relay may not not be operated. It may have open contacts etc. The power lead to it may be open for some reason. Fuse contacts in the panel may be open etc. Trace with a voltmeter. I suggested you remove the case motor and return the trans back to 2wd until you get a chance to work on it again if you need to use the vehicle. Review my reply about doing this. >>>>IF<<<< you knew which terminals in the motor connector to power from an external source, you could run the motor/trans back to 2wd, same as what the relay does.. I gave you the help you need to be able to use the truck. Do it. Good luck. |
thank u for the reply . I did do as you said truck is back in 2wd now I have pretty much narrowed it down to my transfer case control module being bad . which is the little box that sits in the top of the dash where the middle is. Have to take the cluster cover off to get access to it since I can't really get access with just the radio cover off . would you happen to have the part number for that control module i tried google and can't find anything on it. thanks again for your help
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Last I knew the relay module is not available unless you just happen onto one.
Don't know the p/n. Get one from a yard. Good luck. |
New information
i got another 4x4 control module that goes up by the cluster and confirmed it clicked when I plugged it in and got a new switch for the dash selector just to be sure from auto zone. I checked the resistants on the switch and it is changing when I turn the switch so all should be good with those 2. Transfer case shift motor is new but still it won't turn when switch is moved in different positions with the truck in neutral or going from drive to reverse. Even though the control module clicked when I plugged it into its power source it doesn't click when I move the switch . I have checked all fuses associates with 4x4 they are all good tested via test light and visually inspected . I know their are two delays under the dash which control the blankers and the blower for the ac. I have also heard of a RPO block that supposly houses 4x4 relays no idea how to get to that one or its location if someone could point me in the right direction I'm at my whits end ive been a solid week trying to figure this out
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Please read carefully.
It was not the switch to begin with. The dash switch only puts a request in to the GEM to function the case motor. The GEM operates ONE relay to pass 12 volts to the case motor so it runs to the first position in 4H or the second 4L depending on the dash switch position and meeting the requirements of 4L operation. If the case motor does not move for either 4H or 4L it's not getting any power through the relay. The second relay REVERSES power to run the motor back to 2wd for both 4x4 conditions.. If neither direction works, it's not the relay module but open wire harness at some point.. If the case motor will not run either direction; the power supply is missing to the relays or they are not operating to pass power to the motor. This is where your at. Do not replace any more parts until you have verifiable proof of a fault (besides) there is no power to the case motor. To make troubleshooting a bit easier, remove the case motor, keep it plugged up and use it to verify when it moves either way for test purposes. The relay module is in the TOP center area of the dash. They are hard to come by new so a yard source is the next best place to find one. I have explained everything you need. Slow down , think and use common sense. There is no more to this. |
I already replaced the module at the top center of the dash with one from a yard . it clicked for a second when I plugged it in. And as I said I verified power at all the fuses that I could for the 4wd . what is a "RPO" block ? I keep reading about it and that it has a clutch relay for the 4wd. I guess what I'm saying is what does the "RPO" stand for and I'm just trying to get my truck fixed right from what ive seen this system works the same as the 4wd system on a blazer thus the actuator/vaccum i understand that part. I understand what the motor is supposed to do. I understand that I have power at the control module in the dash and verified that it did click. i checked the switch for good measures I didn't think it could have gone bad just like that but it was worth checking to me . I mean i really don't understand what it is that I could be missing here. All fuses where checked via visual inspection and test light and I tested the sockets that I can get to with a test light to verify power to where the relays are I can't find weather or not mine has the "RPO" block though I saw 97 does so im assuming 97-03 would but can't find that info on any forum. Thanks again for the reply
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The RPO 'block' is located about opposite the passenger side's 'air bag cover' toward the 'top left ' of cover area, under the dash.
Review: 1. The Gem operates the relay to power the case motor. 2. This relay passes separate fused power to run the motor. If the motor does not move, stop at this point and find out why there is no power being passed to the case motor. Is there power to the relay? If yes, the relay is not being operated to pass it on to the case motor. If the case motor is operated but does not return to 2wd position the reversing relay is not operating or is faulty. Note; a DC motor will run each way when the polarity is reversed the same as the window motors and door lock motors do. If no, the main power to the relay is open/missing. You have either; A. Main power missing from the fused source. B. The relays are not being operated by the GEM. Note' if the case motor moves at all, the power 'to' the relays is good. C. The relay is faulty. D. The harness, plug or connections has a fault. There is no more to this. The electric clutch is internal to the transfer case and synchronizes the gears for on the fly no grind engagement. |
Your right there is no more to it I hooked it to a 3 way switch and it works the same as it would with the switch on the dash problem solved in my book . besides I found the rpo block everything was getting power changed the control module and also verified it had power to it and also rechecked all the wiring going to the motor as well to the switch on the dash all was good got tired of messing with it after a month and I know the way I hooked it up isn't the "right" way but it works and I'm satisfied with it .... Thank you for trying to help though I appreciate it a million
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