I have an 02 F250 with the ESOF 4x4x switch. In the past year it has been off and on working, low range has never worked...today it finally quit working. I put it in N and switched to 4 high light came on then switched to 4 lo 4x4 light went out no 4 lo light or no 4x4, never did get it to work. Reason for my thread is what can I test before buying a new transfer motor. I did try tapping it with a hammer, unplugging/plugging the connector for it though.
Thanks

 

You did have it neutral with your foot on the brake when you tried 4 low??

 

Have you checked for vaccume leaks? I would start there.

 

That would be my next guess well. As they have been working on and off and now they don’t work at all. Change hubs out with some WARN’s and you don’t have to worry about vacuum leaks anymore.

 

Bench test the 2 ESOF relays. Pay particular attention to the normally closed contact 87a to make sure they have continuity when relay is not operated. Also clean the spade terminals before plugging them back in.

 

X2 to what SARDiverDan said. Mine didn't work when I bought it 2 years ago, and I put manual lockers on it and haven't had probs with it. There's a how to write up on the forum (don't remember where, but it's almost a plug and play kind of thing)someone will chime in and tell you where it is.

 

Yeah I had it in N and brake on for 4 Lo.
1-Where are the ESOF relays located.
2- Am I to check continuity between 87a and 30 or??
3-What method works best to check for vacuum leaks. and i'm guessing to check at the hubs and where else.

 

The vacuum pump is on the right inner fender. If you have a leak you should here it run in the A.M. after you turn the key on. I had a gray vacuum line coming out of the firewall and the end was floating and causing a leak. If I am understanding correctly, with manual HVAC this line is plugged off. I plugged mine to a pin on the AC dryer, I think.
You can also just unplug a vacuum line and then turn the key on to see if the pump is working.

 

ESOF relays are in a separate box under the hood.

Mine are here:



Check for continuity between 87a and 30 with relay non-operated and 87 and 30 with relay operated. These relays operate x-fer case shift motor to shift to 4x4 high and 4x4 low. A vacuum leak will not affect the shift motor, but will cause the non-engagement of an auto hub.

 

Do these trucks have an open transfer case or what? My pickup has never shown to have even a slight advantage in 4WD. Case in point, at the boat ramp, I put it into in 4WD to pull of ramp into the mud...only one back tire spun when I hit the mud. I have noticed that the hubs are clicking in and everything is working properly, do these trucks not have a proper "4WD" system or what? My older Nissan pickup with a locking transfer case will out perform this rig all day long, what the heck? Don't get me wrong, I love the powerstroke power baby, yeeehaaaawww!!!!! Just want a good hunting truck with class, haha.

 

Is this a real quick burrrr, right after you turn the key waiting for the gp's to heat up?

 

No. I am not sure what the quick little "ROMP" is.
If you have a leak,the vacuum tank will empty itself without electrical power. Go by the Picture above and listen there.

I am sorry. the picture is of the relay, the pump is on the other side.

 

The 4x4 didn't work when I bought my truck 2 years ago. Got stuck in sand and needed a wrecker to get out. Did some research here on Ford Trucks, and learned that the hubs go to hell after awhile, so I changed mine and have had nothing but good luck with the manual lockouts.

 

408W: Check out the first line on this page under maintenance tips. Jim

Powerstroke Mods and Maintenance

 

Mine quit a few years back and the vacume line on top of the wheel hub was cracked (dry rot) I cut it back just a little and reinstalled and all has been good since. There is one on each side that controlls the lock .