Auto with Electronic Shift on fly
I am at a loss. I recently put my truck in 4HI, got out of the predicament that I was in and went to switch back to 2HI. It stayed in 4HI. I manually unlocked my hubs and drove the 5 miles to my home.
Once there I began troubleshooting to get it out of 4HI. Nothing worked. In a momement of stupidity, I switched to 4lo and got stuck there.
I know that many forget the proper procedure of putting the tranny in neutral and pressing on the brake and waiting 15 to 20 seconds for it to disengage, but I didn't. I did all this and it won't come out.
Towed it to my mechanic who suggested I bring it to a local dealer. They did a diagnostic and recommended that I replace the transfer case shift motor for $860.00 for starters, but could not guarantee me that it was the problem. They said that there was power down to the motor. I ordered the same unit on Amazon.com for $103.00 and installed it. Same issue exists.
I read other posts online that stated others with similar problems fixed it by replacing the brake switch on the brake pedal. I did this too and no fix.
All 4x4 related fuses are good. I am stuck. Any ford gurus out there have any suggestions? I am way out of my comfort zone now.
Somewhere on the drivers side firewall, near the brake master cylinder, is a box with two identical relays and nothing else. It is usually taped with black fabric electrical tape from the factory. These two relays are what control the shift motor on the transfer case. One of them turns the motor one direction (from 2WD to 4WD to 4LO), the other one turns the motor the other direction.
Since you got into 4WD and then 4LO, it's a safe bet that the motor is OK. So this would make one suspect the relays.
Take the relays out, check for any corrosion around the base, and then put them back in, but swap the positions. The "in" relay should be good, because you got in to 4WD. So by moving it to the "out" relay position, you should be able to get it back out. You do need both relays in though, because the opposing relay provides the ground for the motor.
If swapping the relays fixes the problem, go to Ford and get two new ones. They are less than $20 each as I recall.
I tried swapping the relays but no luck. Thanks David, for the suggestion. Sounded like that would be the issue.
I removed the motor from the transfer case (but left it connected to the wiring) and turned the selector switch to change from 4wd to 2wd. Though the motor twitched for a split second, it wasn't enough to turn it fully into 2wd. I bypassed the switch and ran power from the battery to the 2 pin connector on the motor and it worked. Then I ran power to pin #2 and it turned the other way. This is the method I used to put it back into 2wd. With this new info, any thoughts? Should I just buy 2 new relays and rule that out? I am concerned that there may be a short in the harness somewhere.
It is possible it is still the relays. Before replacing them, however, I would carefully check the relay bases for any signs of corrosion. I believe that the wires connect to the relay box with a connector also. You should be able to lift the relay box out and look at the wires connecting to it and examine them closely for corrosion also. You may also even be able to trace the wires as much as possible looking for any kind of chafing and damage.
Also, check the wiring at the motor for corrosion. There are two plugs to the motor. A two pin and one with something like 4 or 5 pins. Check all of those carefully.
I would get a scanner and check for any hidden codes. The 2005 f-250 has a 4X4 control module which can go bad and could cause a problem like this. The module can set a DTC. The relays that dchamberlain had you pull and switch are controlled by this module. It also looks like the module is located under the dash on the passenger side. I would check for moisture under the dash on the passenger side to make sure a window leak is not causing any corrosion. If I think of anything else I will post.
My OBDII scanner appears to only read vehicles up to model year 2004. I will have to see if there is a flash upgrade for it to read additional model years. If not, off to get a new one..
I pulled the covers (top and Bottom) off the double relay box. Clean on top and bottom (pics below).
As for the module on the passenger side under the far right vent, it is as clean as a whistle. I didn't even bother taking a pic of it.
Now as for the 2 pin and 6 pin connector on the xfer case motor.. I pulled the tape off of the end and they look questionable.. I am not sure if a lazy tech just poked a tester through it last week or if the poke holes have been there for years and just went bad..
I think you are right the wires look like someone tried poking through with a meter or something to get a reading. The connections themselves do not look bad to me and unless the wiring is completely broken through I do not believe that to be the problem either. The relays look clean but its the contacts of the relays on the inside that I am concerned with. The two relays control power to the motor itself. When one is energized it supplies power and they other one has to be off to supply the ground. When the relays reverse their position it then switches the polarity to the motor and makes it drive the opposite way. That is the two wire plug going to the transfer case. The 4X4 control module controls the grounds going to the coils of those two relays. When you throw the switch on the dash from 4L to 4H the module knows what position the transfer case is already in and which direction to turn on the relays. The 6 pin connector going to the transfer case I believe is what tells the control module what position the transfer case is in. If you can figure out a way of measuring the voltage to the relay coils to see if the control module is putting out the correct signals that would isolate your problem down.
I looked at the pics and the relays look pretty clean. No burnt contacts that I could tell. Well you know the motor is good because have proven that already. The relays do not appear to be bad. The wiring has some marks on them but I am not convinced they are bad. The connectors themselves did not look bad. It is now time to check the control module by monitoring the output to the relay coils to see if the correct relay comes in and holds in to supply power to the motor for it to drive from 4L to 4H.
I took a pic of the module under the passenger side dash. I added it to the link below. Is this the right module? I googled the part number "5c3t-14b205-AA" and it just says it is a chassis computer. Some ambiguous posts say it has to do with the airbags but other functions as well..
..And, by the way, I can't thank you guys enough for your help. If you guys that assisted run into any computer systems questions and need advice, private message me and exchange email addresses. I will get back to you. I have 13 years in the IT field and I would be happy to return the favor.
As 3000 FPS mentioned you should at least be able to hear/ and or feel (grab the case while you engage/disengage) each relay coil engage as you switch the 4x4 switch.
You can also check the relays on the bench by applying 12v to the coil and confirming that you have continuity through the contacts when the coil is energized.
The relays have NO and NC (normally open/normally closed) contacts (and one common terminal for both contacts) so you will have to confirm both. If they both test fine then there should be an issue from the relay base to the connector.