4 Wheel Low will not engage,4 High is good to go!

[Doughface1]

I have a 91 Explorer Sport,that has been in a trans shop and they cannot figure it out.
The flywheel and torque converter were replaced,since the whole truck was about to shake itself apart,and even some of the bolts that hold the trans and oil pan had come out and were lost.
The problem I still have is the thing will not go into 4 low,period.
I have replaced the transfer case motor,and they checked the computer in the rearn of the truck by taking one that did work and putting it in and mine in the other.Mine worked in the other truck as well as the switch in mine.But not in mine!
There are two vacuum lines on the engine manifold that are broken,I am wondering,does this system use vacuum as well,although it is electronic,and if so where do these lines go to?
I know it has to be in four high and neutral with the brake applied.The shop told me it has to be a broken wire,but quite frankly after paying for a motor that I did not need I am leery of their advice.

 

[93TwotoneXLT]

Did you install the shift motor yourself? If so did you or the shop that instaslled it cut the brown wire that goes into the pigtail? The symptom you are describing sounds like the brown wire is not plugged into the pigtail, which is then plugged into the harness that runs up to the switch/computer,etc. If you or the shop cut the wire then you will need to splice that wire and plug it into the pigtail then plug the pigtail into the harness. If it has not been cut (doesn't sound like this though) then you can fish the brown wire out of the old pigtail and insert it into the new pigtail. Also, there is a green and a blue wire that also plug into the new pigtail as well. If you follow these wires from the pigtail they go into a magnet that is plugged into the transfer case. Make sure that you do the same for these wires as the brown wire and make sure that they match up with the green and blue wires on the harness. That brown wire being cut and not plugged in will not allow your 4lo to work, only 4hi. Hope this helps and welcome to the site!

 

[Doughface1]

Appreciate the quick reply,am about to go check what you suggested. Am in the process of completely restoring this,and have to say it is The Best truck I have had.At least it suits my needs.
At the back of the engine there is a small vacuum device that has several plastic hoses coming out of it.Two of them are snapped off,any idea where they might go to.
Thanks for the help.

 

[93TwotoneXLT]

If you are talking about the vaccum tree at the back of the intake manifold, then I know what you are talking about. If you follow those lines to where they go then one goes to the fuel pressure regulator, one to the tranny modulator, one to the vapor solenoid on the side of the driver's side firewall, and there may be one more, but cannot think of where it goes at the moment. However, these will have nothing to do with the lack of 4lo. (Sounds like you have figured that out ) If a couple of those lines have holes in them then it can definately cause some driveability problems. I would suggest checking the FPR and making sure that it is still functioning properly, and replace the small sections of hose that are punctured as they will be of small cost and bigger reward, i.e. better running truck! Hope you get your 4lo back. These trucks really are quite stout.

 

[1-Dragon]

i don't know if u know this, but i read that in the older ex u have to put the car in neutral to get the 4 low engaged
I thought my 4 low didn't work and tried it , it only engages in neutral and not in park like the 4 hi does
i own a '93 explorer

by the way 4 hi and 4 low are both controlled by the shift motor

 

[Doughface1]

I have tried everything and still no go on this thing. Are there any relays that might control a portion of the system. I had to recently replace the fuel pump relay,which was a nightmare to find,but that problem is solved.

Thus far,the transfer case shift motor,the switch on the dash,the computer or transfer case shift control module in the rear jack stowage area,have all been replaced,and still nothing. I did in fact even check the brown wire under the truck to make sure it is connected,it is.Na da.

I have the truck in park,hit the four high button,then apply the brake,put it in Nuetral,then try the Four Low,but nothing happens.

It will go into Low if I crawl under it and take off the motor from the transfer case and using a hand wrench,move it into position,so I assume there is nothing wrong other than something not completing the circuit for the Low Range.
Any ideas where to look next are appreciated. Been awhile since I have been able to get on here,but I do thank you for your time and help
Everyone keeps telling me,the odds of ever needing Low Range are slim,but heck if I ever do,I sure do not want to wallow in the mud and crawl under it,remove the motor from the transfer case and use a wrench to do it.

Thanks.

 

[93TwotoneXLT]

I don't know where to go from here. It still sounds to me like the brown wire is not connected somehow, or you could have possible gotten a bad shift motor(even though it is new). If the transfer case was not in the 2wd position when the motor was replaced then that could cause the problem too, although that is doubtful. I am out of ideas from here.

 

[agzaretzka]

Test Procedure

 

[Maniak]

Check the neutral safety switch. The truck knows if its in neutral or not, and if its not it won't go into 4x4 low..

You could put the truck neutral and try to start it. If it starts in neutral but not in drive then the neutral switch is working. If it won't start in neutral then the truck doesn't "think" its in neutral and won't let you go into 4x4 low either.

~Mark

 

[LXNavajo_94]

kinda off subject here but the other hose you were trying to remember there 93twotone goes to the cruise control diaphram if you have one if not its capped