Service 4WD light came on....
 

It's raining pretty good here in Houston and I hit a very large patch of standing water doing about 50 MPH. Water shot up both sides of the truck at least 50 feet in the air! After the water slowed me from 50 to 10 MPH in half a second, my "Service 4WD" light came on and the electronic transfer case switch on the dash usually has a little LED light lit but now it's not lit any more. Could the blast of water underneath the truck have disconnected something or screwed up my 4WD? I will probably need 4WD to get home and it won't let me switch out of 2WD. Any suggestions or has anyone experienced this?

I was in Houston this weekend at the Drags in Baytown and hit a lot or rain Sunday. But, you really got it today.

Can you check to see if a fuse has blown? If you can find a dry spot, maybe check the connectors around the transfer case. I'm guessing the connectors are weather pacs, but you never know.

Pete

I would check to see if the vacuum lines on the top of the axel came off. The run back to the transfer case

I'm old fashioned I suppose. On my Larmaie, I opted to delete the electronic system in favor of the lever. I know this doesn't help you, but you helped me by reaffirming why I made that choice.

Now, watch my power windows quit working next time the windows are down and it rains.

I could be wrong but I do not think there are any vacuum lines on our trucks that shift anything on the 4x4 . This is also the first failure I have ever read about and I will be interested in finding out what happened also . Mine has worked flawless and I use it often , at least 20 times yesterday . It sounds like it took a hard hit under neath so that is were I would look . I think all that is down there is the motor and wiring harness so it should be simple to diagnose . All the guys with the old type shift lever on the floor have been waiting for this to happen and I am sure they will come out of the wood work and claim what a piece of junk the electric shift is .

The vacuum lines that go from the transfer case have nothing to do with the electronic shift. They engage the front hubs. On old 94 they ran over to the passanger side. They can pop off easy enough when slamming a few hundred pounds of water pressure on them. So once you find them follow them back to the transfer case. Check to see if they popped off on either end. And call lazy. But I like my electronic shift 4x4

I figured that was maybe what he was talking about when he mentioned vacuum lines but I was not sure . The 3rd generation trucks have no way of locking out the front end, the front drive shaft turns all the time . My guess would be fuse or connection at transfer or maybe a ground wire . I wonder if it will kick out a code and send you in a direction to start looking .

No code whatsoever. I think I found out what happened. The high pressure water forced water into the wire harness that controls the little motor thing because it seems like it got burned out. Smells like it, anyway. The #43 fuse blew so when I saw it, i was thinking that's why. But when i put in another fuse, it instantly blew. I like the electronic switch better than the lever, it's easier and saves floor space. I darn sure wish I had ther floor shifter yesterday though![dummy]

Sounds like you found the problem , in my thinking the only way that the motor would burn out is if it got power some how . I would be looking for a shorted wire some were that caused the motor to stay on and burn up . Please keep us up dated on cost and what you find , thanks

I have an 07 6.7 3500 and it is not going into 4wd when i want it to. and it is going into 4wd when i dont want it to. the 4wd service light come on and off there is no rhyme or reason. the actuator clicks in and out when the truck is off and parked. like ill get back from town and unloading groceries and can hear it kicking in and out no keys in it and nothing turned on.

I have the exact same problem. I replaced the dash 4x4 switch and the transfer case drive motor. After about 10 minutes of driving the service 4wd light comes on and engages into 4wd without watching it. I park somewhere for a while and it goes back to normal till I drive 10 minutes or so again. If you found the answer. I would greatly appreciate it. You’re the only one that I’ve read that’s had the same issue.

I replaced the actuator on the transfer case and fixed my problem.It seems like it is not just a motor but there are sensors in there too and that is what was wrong with mine. I kept telling myself it could not be the actuator because it is shifting I was leaning more towards a wiring problem. Everyone said dont by a reman but i went to autozone gave two hundred something for a reman with a lifetime warranty and I figured it is easy to change takes about ten minutes. So since I put the reman actuator on I have not had any problem (knock on wood) and cured all the other problems I was having. Hope this helps good luck

4wd issue
 

mine has done that a few times to me to. It seems to only occur in rainy days