ESOF not working, no 4x4 at all.

Thecodymanley

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dash lights do power up at key on, no 4 high, no 4 low. all vacuum components are removed resulting in only manually locking hubs, trying to get the in cab switch to activate the transfer case.

The issues is there is no power getting to the actuator on the transfer case, all fuses check out okay.

Any input? thanks.
 

bismic

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I don't believe it is PCM controlled, I believe the 4WD module is behind the glovebox (WSM 308-07A-71). What year model truck do you have? You can easily pull the glovebox and inspect the wiring. Does the 4WD switch on the dash provide power to the relays? If the degas has ever puked, these relays can get corroded.
 
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Broke4smoke

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If you ever washed your motor usually the relay gets water in them if you want to test the relay switch with the FICM relay ... the FICM relay is behind or in front of these relays can't remember
 

bismic

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You can swap the two relays (they are identical). One engages 4WD and the other switches back. Since you can't switch TO 4WD, maybe the other relay is still good and swapping them should identify the problem.

Did you check ALL fuses involved?
fuses #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.
 
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Thecodymanley

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So pin 3 on the dash switch (12v voltage reference) into the switch where there are 3 resistors. 6xx,3xx,and 1xx ohms causing a voltage drop on the return pin #2 which feeds back to the 4wd module.
Pin 3 has 12v unplugged but when plugged into the switch itself it drops to whatever pin 2 (signal return) should be and the signal return has 0 volts always.

Now from normal operation it should be 12v voltage reference constant into the switch (pin 3) and the signal return (pin 2) should return the voltage with the desired voltage drop depending on where the dash switch is (2wd, 4 hi or 4 lo) thus leading me to believe it is the switch itself or the 4wd module.

For the record all fuses/relays check out. Also on the transfer case, the sensor which indicates position has power constant on 4pins, ground constant on 1 pin. Now the strange thing is there is intermittent power flashing with no rhyme or rhythm on another pin roughly in the same intervals as a flasher,, any input of this is normal or not?

Thanks
 

Thecodymanley

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Also, there is 2 constant power to both relays. Pin 30 on both relays had strange ohm values in relation to ground. There was 10-500 ohm resistance im not sure where these grounds come from but possibly through the 4wd module. Also the relays are ground activated supplier by the 4wd module on pin 85 or 86. I am not getting ground to the coil in the relay to activate it. Which again leads me to believe switch or module
 

powerlifter405

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I had a no ESOF issue. Ended up being the GEM under the dash, acquired used off ebay works like a champ.

IMHO if you intend on keeping this thing get the ford manuals. I did the trouble shooting, did vacum testing etc in a few hours and had the GEM ordered up.
 

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