Way to be short sweet and to the point Mark I laughed after reading that

 

Unplugged the sensor with no change. Checked both wires and neither one is grounded. I can't quite get on the terminals in the plug, but all the dash lights work for 4x4 and low.

 

700 hp oughta clear up your problem.

 

So you checked the wires on the truck side of the plug and neither one is grounded to the body?

And the 4x4 and Low Range lights work normally when the sensor is plugged in and you shift the transfer case?

And the code came back with the switch unplugged?

There's got to be a reason why the PCM thinks that the low range sense circuit is closed to ground even with the switch unplugged. Only reason that could be is a short to ground.

Anyone have a schematic handy?

 

That's correct. And guess what? This morning it's shifting normally. It must be a short to be causing this problem and then "correcting itself."

I'm not certain (my buddy is the electric guru, not me) but I think the schematic shows the switch to the PCM, and the PCM to the lights. Maybe Mark will chime in here...

 

4L switch triggers the Instrument Cluster lamp and feeds the PCM 4L signal input

 

The circuit labeled 784 in the diagram above is the circuit that you need to look at. That one is being grounded intermittently.

 

So where it splits off and goes to the PCM is where I should be looking.

 

check out right as the wires go up in the harness by the frame.towards the front drivers side of trans.sometimes this harness can chafe right there on the frame.if so,repair all wires,liquid tape etc.and wire tie back up and away.next i would pull,inspect and clean the harness at the pcm.
look very closely at the wires under the loom by the 4wd switch.it could be shorting out right there.if you checked there,do it again for good measure.

 

Thread Revival: Hello All My name is Frank and i am a new member..I am posting on this thread because i don't think it would be a good idea to start a new thread with the same or similar title when there is so much good information on here.. If i am wrong i apologize in advanced and would appreciate any information i could get on this issue..

So I am having a similar problem as the OP but mine is mainly 1st to 2nd shift its like if 1st is a granny gear for me and would shift to 2nd at about 1mph its almost immediately then 2nd feels like its weak and i get higher revs with the pull tilll it goes into 3rd which seems fine and so does OD.. if i manually shift it im fine but i do notice 2nd still revs higher than it should and 3rd grabs fine. im thinking 2nd may be glazed but cannot understand why the quick shift from 1st to 2nd.. i have no codes i have been dealing with this for a couple months since i got the truck.

background on the truck i got it with what was supposed to be a bad trans. no movement at all PO told me it just quit moving.. started checking and found no fluid in it. i added 7 qts and it caught but wasn't right still . i dropped the pan and found filter was in the pan and the neck was melted so it could not stay in place.. I did lots of reading and hitting forums and came to the conclusion he overheated the trans.. I drained all the fluid also TQ fluid and blew out the cooler re filled with new fluid and filter and she was working ok besides a couple min delay to engage gears which leads me to belive the seals got hard and it feeling like it was taking off in 2nd all the time unless i manual shifted.
then 1 day it went into limp mode and i pulled all codes and traced the issue to the sol plug.. replaced that and all codes are gone and no more limp mode but i still have that quick shift issue.. Any info on where i should look next for the cause?

 

I'd start a new thread. Your problem is very different.

 

Noted and done.. My Apologies

https://www.ford-trucks.com/forums/1...l#post16172330

 

Hey guys! Sorry for digging up an older thread,.. but our 97 F250 HD 4x4 is exhibiting the same symptoms as the OP's -EXCEPT that I have no lights on the dash, everything looks normal.

It ran fine last week, and my son hopped in it today as it was raining cats and dogs here and didn't want to drive his Mustang...

He got home and I took it for a test drive, same thing,.. starts out in first for about 5 ft and then seems to shift up super fast all the way to OD and then down shifts, then back up real quick. When manually going through the gears it seems to do fine....

I'll use the info above to start diagnosing the problem..

Here are some other points of interest..

1 - Just had new tires put on it a week or so ago, but ran fine afterwards.
2 - Recently had problems with the Left front manual hub lock out not disengaging, but went through it and it's working fine now
3 - For giggles I thought I'd put it in 4x4 but couldn't get the manual lever to move - but still drove fine after that....

Thanks
Rick

 

It's really best to start your own thread instead of digging up a really old one. For your 4x4 lever, you'll want to take the linkage apart underneath and clean and grease all the pivot joints. If you try and force the lever, you'll almost certainly break the aluminum casting.

To get started though: You should verify your speedometer is working correctly, and check for codes even if you don't have a check engine light.

 

I am working on a 1997 F250HD 5.8L E4OD (Manual Shift Transfer Case) doing 100% the same thing. Did you ever find the solution?