I have 2004 Navigator with low mileage (61k) and recently we had a crazy cold weather up in northeast. I don't know if that's what it caused, but since 2 days ago, my car's liftgate won't open/close automatically.
I figure the 'hook' at the center of the gate isn't 'hooking' whenever the gate closes.
Can someone give me a tip how to fix it?

thanks!

 

Can we assume you checked for a blown fuse?

 

You mean the fuse box by the passenger side feet area?
How do I know the fuse is blown? Is it black like a burnt wood?

 

Yes that's the one. Look at fuses #5, #30, #102, #105, and #110. Those all in some way relate to the power liftgate circuits. Take a look at the images below which show comparisons of good versus blown fuses.

 

thanks! I'll check it tomorrow and let you know.
Just in case it is the fuse issue, where can I purchase new fuse?
Car part places like Autozone would carry?

 

Car parts stores, Wal-Mart, hardware stores, CVS, Walgreen's, local convenience stores, just about anywhere. Just make sure you replace any blown ones with an identical amperage rating/color.

 

To be sure, you can also beep it out with a multimeter, if you know how to. That will confirm that it has continuity, as in rare cases the fuse might look fine but there's no continuity through it, it has happened to me before, and I know others who ruled out fuses and started swapping parts, and you can imagine the look on their face when they found out it was a blown fuse when it still didn't work...

 

Okay, just checked all those numbers in fuse box. Everything is okay except #110. The manual says #110 controls the running board at the bottom of the doors for extra step.
My car purposely disabled that because being 10yr old, it started get rusty and about to fall off every time the running board came out when we open the car doors. So we went to local shop to disable it. I guess he 'cut' the fuse on purpose so it doesn't come out anymore. I know this isn't the issue because we disabled this feature over a year ago and the liftgate was working just fine up until few days ago.

So... besides fuse issue, what'd be my next step?

 

I even tried switching with same Amp fuse of another # to make sure the fuses are okay, and they are.

 

You need to test for power at the liftgate motor and work your way back to the switch to see where the power stops.

 

wow... that sounds rather very technical
how do I test power?

 

Do you have a digital volt meter (dvm) to be able to test with?

 

You can also make the running boards not come out with the settings in the message center. Put a good fuse back in and change the running board settings. I turn mine off when I put my Navi on a lift.