4X4 actuator grinding noise
 

I have a 2007 Navigator and was having issues with a grinding noise when in 2WD but associated with my 4X4 actuators. The noise would stop if I activated the 4X4 button on my console and the 4X4 message would read 4X4 in the message center. I started out by changing the Hub Lock Vacuum Solenoid. This seemed to eliminate the noise for about a week, then the grinding noise returned when in 2WD. After inspection of the Hubs and 4WD Actuators, and the front Axles, we found there were metal grindings present and the edges of the gears were worn down. I replaced both left and right front Axles, both 4WD Actuators, both wheel Hub Bearing assemblies. While I was at it, I replaced both left and right calipers, rotors, brake pads, brake hoses, and ABS sensors. The noise has stopped, but now I am not able to engage the 4X4 or Auto 4X4 using the console buttons and there is no read out in the message center. The auto shop I used to diagnose this thinks the 4X4 control module should be replaced but claims the part is no longer available from the dealer.

I don't really use the 4X4 because I live in the south, but I am concerned that the issue might repeat itself if it's not operating properly as designed. During this process, after searching my owners manual, I located and pulled the two fusses, # 35 and # 75, associated with the 4X4, from the fuse panel located under the hood near the radiator, to make sure it wasn't a fuse problem. When I reinstalled the same good fuses, the 4X4 message would display on the message center when I pushed the 4X4 button and operation seemed normal. I was able to turn the engine on and off and it continued to work correctly. I thought I had reset the computer, but after sitting overnight, the next day, the system reverted back to not responding to the activation of the 4X4 button and no message of 4X4 in the message center. Same old, same old, and it's been that way for the past several days now.

Has anyone else had this same issue and if so, how did you fix it? Or, do I even need to fix it if I don't plan to use 4X4? Did you have to replace the 4X4 control module? And, if so, where is it on my 2007 Navigator?

Thanks in advance for any and all responses!
Dale

Vacuum disengages the front hubs from the front axle shafts.

When you place the vehicle in 4x4 mode, vacuum to the hubs is shut off so the hubs engage the axle shafts.

When you place the vehicle in 2x4 mode, vacuum is applied to the front hubs disengaging them from the front axles. If you have vacuum leaks or insufficient vacuum to keep the hubs disengaged, they will partially engage and the gear teeth will make a grinding noise. If you then put it in 4x4, the vacuum is cut off and the hubs fully engage and no more grinding teeth.

PDQFORD, that's my understanding of the vacuum operation too. That's why the first thing I did when I heard grinding was to replace the Hub Lock Vacuum Solenoid. I don't seem to have an actual leak that I can tell or I would have other vacuum issues and throw a code, at least that's my understanding, and please correct me if I'm wrong. What my issue is now, my message center is not responding and displaying 4X4 or Auto 4X4 when I press the corresponding buttons on my console. I am trying to figure out the fix for that. Any suggestions?

Is the shift motor on the back of the transfer case stuck?
Does it try to move when you shift to 4x4 mode?

pdqford, checking the shift motor sounds like a two person job, one in the driver seat and one under the vehicle. I will have to get some assistance and get back to you. Thanks,

This is an electrical problem that started happening immediately after you did work on the vehicle. I would focus on the electrical work you did. It sounds like the only electrical components replaced were the ABS sensors.

I'd start by suspecting the ABS sensors. Are they installed properly. Maybe they're the wrong ones. Try putting the old ones back in and see if the 4wd works again.

To follow up on my actuator grinding issue, it took four months for the grinding to return on the drivers side. Apparently this is a chronic issue! This is what I ended up doing. I replaced both left and right side vacuum controlled 4X4 actuators, yes, the ones I just replaced 4 months ago, with "Dorman 600-405 4WD Hub Locking Actuator Delete Kit", $250 list price or $80 on Amazon. It replaces the vacuum controlled actuators with non-vacuum controlled actuators, that eliminates the need for vacuum and keeps the actuators engaged full time. The CV axles turn all the time now, but the transfer case is not engaged and not providing torque without pressing the 4X4 button. So, I still have the capability to have 4X4 if desired without it being full time 4X4. With the actuators engaged full time, there is no longer any way for the grinding to return. The axles now turn full time just like on other 4X4 vehicles, like some Dodge and Jeep setups, and that is fine with me. I have piece of mind again!