4 wheel drive not engaging

[gfyracing]

4 wheel drive is not engaging on my truck. When I turn the dash selector to 4 hi or 4 low, with it in neutral or park and my foot on the brake, nothing happens. I don't get any clicking from the 4x4 control module and no lights flash on the dash. When I start the truck both the 4 hi and 4 low lights come on for a split second then go out. We have had periods of -20 here lately and I have had battery issues. I have heard this can cause the 4x4 module to fry but from what I have read the 4x4 lights both shouldn't flash when the truck is started if the module is fried. I've tested all my fuses and they seem good so I believe the 4x4 module is the culprit. I find power coming into the module but when I test the 2 middle wires going to the switch there is no power to them. I know the switch is a resistor so I am assuming that those wires should have enough voltage to light up a test light. If there is no power in those wires would it indicate an issue with the control module? I know there are a lot of posts about this issue and I have read through countless ones but I don't see any that mention both 4x4 lights flashing on startup.

Thanks.

 

[Lonnie-S]

From what you've written, I can't say what your problem actually is, but here are a couple of things I've encountered reading these forums.

1) Their a several circumstances when the 4x4 lights will flash on startup, and even at specific intervals after the vehicle is running. Here is ONE context for a regular Explorer ==>

It sounds like you have done a good job of testing for fuses, etc. If there's no current going to the shifting servo, obviously nothing's going to change.

2) I have read of circumstance where the servo motor itself freezes up mechanically. Also, have you checked for any inline fuses for the servo motor wires too? I don't know that there are any, but worth checking the line(s).

3) The 4x4 control module has to know the transmission is in neutral, at least if you have an auto trans. Is there any possibility of a problem there?

4) If you do a search here, there is a thread on changing out the 4x4 control module.

Good luck,

 

[gfyracing]

Thanks for the input. I haven't gotten under it yet to check the actual 4x4 engagement motor because I'm pretty sure the issue is up from that, there are no clicks when I select 4x4 high or low so no signal is being sent to the motor to engage 4x4. I think I am going to get a replacement 4x4 module form the junkyard to see what happens.

 

[gfyracing]

I got a 4x4 module from tge junkyard and have the same results. When it starts both 4x4 hi and low lights show them go out. Nothing happens when i turn the selector switch to 4x4 high or low. There is no click of the relay. I rechecked all the fuses. If the motor or servo didnt send the correct signal wouldnt the relay still click and try to send power to the motor?

 

[Moparonly]

I got a 4x4 module from tge junkyard and have the same results. When it starts both 4x4 hi and low lights show them go out. Nothing happens when i turn the selector switch to 4x4 high or low. There is no click of the relay. I rechecked all the fuses. If the motor or servo didnt send the correct signal wouldnt the relay still click and try to send power to the motor?

You Ever find out what it was,I have the same problem

 

[Moparonly]

You Ever find out what it was,I have the same problem

I found the problem It was a broken wire down near the actuator