Well to start off some background info i suppose:
Vehicle: 2002 F350 Crew Cab Lariat 4x4 automatic w/ ESOF (Electronic Shift on the Fly)
Miles: 167k
Ok now to my problem...So just recently I've started having some problems with my 4wheel drive. I used it last weekend and it worked fine then on thursday the 4x4 would not engage (and light on dash would not come on). Neither 4high or 4Low would work, either by manually getting out of the truck and locking the hubs in or using the ESOF. I did some searching under the hood and found that a vacuum line coming from the Pulse Vacuum Hub Lock Solenoid had come apart at a connection point. I reconnected them and the 4x4 worked for about a day and then quit again. I checked that connection again and it was fine as were all others along the vacuum lines. I know that when there is a vacuum leak the heater will default to the defrost posistion. When I turn the ESOF switch to 4high or low the heater does not do this, so i guess no vacuum leak (please correct me if im wrong). Saturday I went into the gas station to get some food and left the truck running (with it in 2wd and hubs on auto ESOF switch on 2wd), when I came back out, 5 min later, the 4x4 light was on and the truck was in 4high (mind you the hubs were still on auto and the ESOF switch still set on 2wd). I switched the 4x4 switch on and off a few times before the light finally went out and the transfer case disengaged. This kind of led me to believe that my 4x4 switch could be going out...im not sure but before I go dumping any money into the truck i was just curious if anyone had any ideas what my actual problem could be??? Are there any tests I can run on other components to rule them out? Thanks for the help in advance guys!
Run Down of Problems:
1) 4x4 high or low will not engage manually or by using ESOF switch (4x4 light does not come on)
2) 4x4 Sometimes switches itself on with the hubs in auto and ESOF switch set at 2wd (4x4 light will come on)
3) Often when the 4x4 is engaged it will not disengage
4) All vacuum lines connected
5) No vacuum leaks (I think, because heater will not switch to its default, defrost posistion, when the ESOF switch is set on 4x4)
6) There's snow on the ground, the 4x4 wont work and I need a beer!! haha
after chasing minor esof problems on my new to me 03 f350 crew cab long bed 6.0l 6spd manual. this site told me this much. the light on the dash is controlled by the switch that tells the electric actuator in the t-case to move. if it does not engage the light won't come on. the light will come on if the t-case engages even if the hubs don't. the auto lock hubs with vacuum control are seperate in all ways except the switch on the dash. i would start with the switch and wiring to the t-case. the vacuum system is simple and sounds like you might understand that. my problem was a cracked soleniod for the vacuum hubs. i would look for loose wires in to the switch first if it appears to be erratic.
I just had the same problem, check your switch and see if you have power to the back of it. If not, according to another forum this means your 4x4 control module is bad. I only had power for the indicator light and nothing else.
Ok,
I would turn your switch to the 4x4 position, if the light does not come on indicating it is in 4 wheel drive then check for power at the back of the switch. If you don't have power it should be your module according to other posts I have read.
Well i disconnected everything from the switch and cleaned all the connectors off (they weren't too dirty however), then reattached it all. So far so good, however i've only tried to use the 4x4 twice since then, i'll check out the connections on the t-case this afternoon and make sure everything is connected and powered right down there. Hopefully this solved my problem but if it happens again i'll have to check the power to the back of the switch like you say. Where is the 4x4 control module located if it turns out that there is no power to the switch???
For mine I just open the glove box and push the sides in to get it past the stops. This gets the door down and out of the way. Then you have to look in and up to see the module. I hope this makes sense.
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