I've searched, but didn't find what I was looking for. I have a 2003 7.3 auto with ESOF. Auto hubs have been converted to manuals. 4WD doesn't work. I get the 4X4 and LOW lights light up when I start the truck. The shift motor was disconnected when I got the truck. I assume the previous owner was having trouble and starting diagnosing.
I have no power to the ESOF switch. I am diagnosing based on the assumption the ESOF system works like this: Power (12v) goes into the 4X4 module. From there, 5v (vref) is sent to the ESOF switch. The switch creates resistance depending on where the selector is set. Based on the returned voltage (due to resistance) the module sends 12v to pin 85 of the respective relay, which energizes and sends 12v from pin 86 of the relay to the transfer case motor.
Based on the wiring diagram I am using it should be getting vref (usually 5 volts) into the switch from the wht/lt blu wire with the key in run, but I'm not.
Ground to the 4x4 module is good (0.5 ohms between the connector and batt-).
How is the 4x4 module powered? Is vref 5v?
If I can verify power into the module and good ground, is there anything else that would keep power from the ESOF switch other than a bad module???
Looking at the diagram right now. The WH/LB wire pin #3 of C294 at the
switch is the signal return and should act like ground on the 4X4 module
side if the switch is open. The Vref looks to be coming from DB wire pin
#2 of C294 at the switch. It looks like the 4X4 module is the source of the
Vref in this application. Pins # 1 & 4 are lighting.
When a line says signal return you can almost always say it will
be a ground line. Just use care to not short anything out. 12V in
the wrong place could be a problem.
One thing you could do if you can get at both ends is check the continuity
of the two wires once you unplug both.
Also unplug the switch and the one that is connected to the Vref should have
Vref on it. (Blue wire pin #2 on C294 If no power then go to the module and
check pin for Vref there. If you can try with the plug unplugged. (you may not be able to)
This is just in case ther eis a short to ground from a damaged wire.
Did some checking this afternoon. The DK BLU wire is the supply wire and the switch is getting voltage. Thanks for the direction, Yahiko!!!
I have already checked resistance in the WH/LB wire - Good.
I checked the relays - Good.
Resistance between pins 30 of the relay connectors and corresponding pins on the 4x4 motor connector - Goodish. (Everything is coated with oil and needs a real good cleaning. I have a good feeling it will be good once cleaned.)
Voltage to pins 87 of the relay connectors - Good.
Resistance between pins 87A of the relay connectors and ground - Good.
Resistance between pins 85 of the relay connectors and corresponding pins on the 4x4 module connector - Good.
NO ground from the 4x4 module to the relays via pins 86. Resistance between pins 86 of the relay connectors and the corresponding pins of the 4x4 module - Good.
I also tested resistance between the center 2 pins of the switch.
2wd - 3.910 k ohms (3910 ohms)
4wd high - 1.098 k ohms (1098 ohms)
4wd low - 357.2 ohms
These readings are all in line with post #8 of THIS THREAD, and show the switch is good.
The only thing left is the 4x4 module. Before I lay down the coin for a new 4x4 module, does my conclusion seem correct?
I think you on the right track but would like to be 100% sure.
Hate spending money and finding out that was not the problem.
Not sure but I think you want to ask if that module has to be programed
or not. Also would be nice if you had access to something like the Ford IDS VCM
to really test it. Have you checked for any codes? The reason I ask is that
it's got commutations back to the PCM and it should show faults.
Now for the fun part. Where in CA are you? I will be heading down I-5
from Tacoma,WA to Los Angles,CA on the 25~26 and will have my Clone
VCM with me and if your not far a field I could run the diag on it.
I will be ending up in La Habra for a few days.
EDIT : Going to add a few goodies for you.
NOTE : I think 34?1 might be the wrong year the others are correct.
I am getting 3 codes: P1000, P0705 and P1702. I'm not worried about the P1000. (Should I be?) The other two have just showed up this morning and have to do with the DTR circuit failure. I had the central junction box out a couple days ago for some wiring I was doing. Before I freak out about these codes I need to check everything and make sure it's all tightly connected. I have another sensor I can replace the existing sensor with, too.
I'm right where the 210 and 215 freeways meet in San Bernardino, about 50 miles NE of La Habra. I can definitely make time to meet you somewhere. Thanks for all your help!!!
P1000 is just a self test that is suppose to go away after you still the truck. My 04 F350 with 5.4 has the P1000 come up ever time I hook my SCT to it and it's been over five years!! I've been told drive it it will go away well in my case it never does
Hello, I am having the same problem. I have new relays, verified voltage and resistance at the switch, verified continuity but no voltage at the solenoid connector, have not probed the 4x4 module yet. Did you end up getting a new 4x4 module and did that do the trick?
Based on other posts, if your dash lights with "4X4" and "LOW" when you start the truck your module is good. My problem ended up being a bad transfer case motor. In hindsight, I think pins in the connector were covered in oil giving me false readings. I happened to have another motor laying around, plugged it in and it worked!