4wd engaging by itself?

[mweiman]

I recently replaced the transfer case actuator motor on my brother's 07 mega cab. The old motor would not engage at all. I removed the old motor and it did not move at all when moving the selector switch. Anyhow put a reman motor on from carquest and it seems to engage 4wd on it's own every now and then. The 4wd light does not come on but you can tell when you turn that it is locked in sometimes. He also said that a few times the four low light will start flashing going down the road. It only does it about every other day or so. Any one ever have this happen before or know how the motor is powered? Does it get constant power with the key on and get a pwm signal to change ranges or something?
Thanks for any help,
Matt

 

[Mark31]

My 04 did that with the Dyna Locks free (so the transfer case wasn't turning) at about 45-50 mph. Talk about a WHAM! Didn't seem to hurt anything--4wd high and low work fine with no noise. I now pull the fuse so that can't happen again. Service 4wd now lights up on the dash. Until someone can convince me that they know exactly what caused the problem and the 100% solution, I'll keep the fuse out with the Dyna Locks unlocked and when locked in if not in a 4wd needed situation. Ain't lectronics wunnnerful!!

 

[mweiman]

I think to start I am going to have to swap a motor off of another truck and see if it still does the same thing. Not sure how else to troubleshoot it.
Matt

 

[MarkEkberg]

I think to start I am going to have to swap a motor off of another truck and see if it still does the same thing. Not sure how else to troubleshoot it.
Matt

Or bring it back and try another. If it does you have a power backfeeding issue I bet.

 

[leaky gasket]

If it is a backfeed issue you need to start checking your grounds.