Ive changed all relays underhood cause i could not find info on which relay is which, checked all fuses under dash. Checked to make sure up stream on 4x4 fuse position has power. And i checked for power at 2 wire on transcase no power at 2 wire, i am also finding no power at back of dashswitch...
Im hoping someone out there might have wiring diagram that shows complete esof schematic

 

Send dchamberlain a PM. He seems to be the resident wiring guru although someone else may chime in with the required information.

 

Ive replyed to a post where he offered info, and i will try to pm

 

I'm assuming your 4WD isn't working, and that the 4x4 light on the dash is not coming on when you switch the switch to 4WD.

First thing to do is to check the make sure the 4x4 light is working. It should come on briefly when you start the truck. If it does then you know the light is working at least.

Find and check fuse #19, 27, 31, 33, 34, 45 and 111. Don't just visually inspect them, take them out and check them for continuity between the pins with a meter.

Get an assistant, get under the truck with a standard test light and find the 2 pin connector to the transfer case shift motor. Unplug that connector and connect the test light between the two pins of the connector. With the key in the RUN position (the engine doesn't actually have to be running), have your assistant turn the **** to 4WD. The test light should flash a number of times as the 4WD module tries to engage the shift motor.

IF the light flashes, then everything upstream of the shift motor is working. Inspect the connector, and the plug on the shift motor it connects to for any sort of corrosion or indication that there might be a bad connection. If everything looks good the shift motor is probably bad and needs replaced.

If the light does not flash then you need to find out why. The next most likely problem is one of the transfer case shift relays. The shift relays will be in a auxiliary relay box under the hood, drivers side towards the rear of the vehicle. They are usually in a relay box by themselves. Two identical relays with nothing else in the box. The box is wrapped from the factory with fabric electrical tape, but that might be gone if someone has already opened it. First thing to do is remove the relays and look for corrosion. If you find corrosion, clean it up good and try again. If that doesn't work, continue to the next step.

A good test of the relays is two remove them and swap their positions. One of the relays is used to turn the shift motor from the 2WD position, to the 4WD position, and then to the 4Low position. The other relay turns the motor back the opposite direction, from 4Low, back to 4WD, then back to 2WD.

When the relays are swapped, try shifting into 4WD again. If it works, you've found a bad relay and should probably just change them both.

If none of this works, then we'll need to look at the relay base wiring for corrosion and possibly move on to the 4WD control module.

 

Nice write up David. Is that somewhere in the tech folder or A tech folder? Somebody rep this man for me as I have to spread the "love" some more.

 

I wish someone would put it in the tech folder. It covers pretty much all of the transfer case end of it anyway. The fuse numbers wouldn't apply to anything but a 2002-2004, though, cause the fuse panels and arrangements had a habit of changing.

 

Thank you much gentlemen

 

I added the thread to the Tech Folder, please Rep David!

 

Thanks David! I recently realized that my 4 wheel drive was not working. I was able to relatively quickly diagnose it as the shift relays. This was an excellent thread. The only thing was different on my 07 was the location of the shift relay harness (driver side, very front behind headlight).

Thanks!

Chumley

 

Hey all,

Great thread and lots of help. I have a 2004 Excursion 6.0 turbo and like others on here my 4wd isn't engaging. Thanks to this thread i've been able to track it down to no power to the fuse 31 in by fuse box. I'd like to try and find out how to further troubleshoot this circuit but I don't have a wiring shematic with enough detail to show me what harness to target. It seems that i have either an open circuit somewhere. Can anyone share more specific info on this one or have a more details schematic they can share with me. Snow is getting ready to fly and I need 4x4. Thanks in advance for any help.

 

For future reference, to get quicker responses it would be a better idea if you were to start your own thread, as opposed to reviving old threads. If you are referring to fuse F2.31 (15A) in the central junction box, that particular fuse is only supposed to have power with the ignition key in the START position.

 

Hey thanks for the advice.. I created my own thread on this topic and am still tryint to troubleshoot the issue. Thanks for the info on fuse 31. Turns out now I have power to the 2 relays and need to move on from there. Any additional help would be greatly appreciated. Please take a look at my new thread.

 

Gotcha covered on the reps Dave.

 

From DChamberlain's Post above: IF the light flashes, then everything upstream of the shift motor is working. Inspect the connector, and the plug on the shift motor it connects to for ................

...........................When the relays are swapped, try shifting into 4WD again. If it works, you've found a bad relay and should probably just change them both.

If none of this works, then we'll need to look at the relay base wiring for corrosion and possibly move on to the 4WD control module.



Does this info also apply to the 2002 F150 4x4 with ESOF?

Thanks

 

I have a 2003 f250 that the 4wd does not work on i have done some troubleshooting
-i have no power to the switch
-i have checked all fuses and everything checks out for good resistance
-i have swapped the relays and did not work
- i have checked at the actuator for test light to flash and nothing came up
- the light in the dash does not light up even when key is turned on
- i have jacked it up to verify drive shaft is actually not turning
- if i jump the ground side of the relay to a ground i can get the 4wd to actuate and im checked all wires at relay so somewhere between the ground signal to the relay and the switch im not getting signal
- on the back of the switch all the wires are ground no matter what position the switch is in

What should i start looking at im thinking my only options now are broken wire before the relays or 4wd module am i correct?