Rear liftgate locking/unlocking troubleshooting

C-ya

Original poster
Member
Aug 24, 2012
1,098
My '05 TB EXT LT has an issue with the liftgate. It got locked and wouldn't unlock even via the Tech II for the last couple of weeks so I couldn't open the back. It won't lock or unlock with the door switch or the key fob. It will, however, lock and unlock with a Tech II since I have opened it up and moved things by hand. It is also saying it is open (via its switch, and the Tech II sees it as open), which means I can't use my rear wiper unless I use the Tech II. I'm not sure which part I would replace - the lock mechanism or the liftgate module. It would seem the signal comes from a different place via the Tech II than the door switch/key fob, so that might indicate the module. I sprayed the heck out of the lock mechanism and even tried to move the close switch (I think...) over a tooth so it would show closed, but that didn't do anything, so I may need to replace it to show the liftgate is closed.

Any thoughts or ideas?

As an aside, I found out why my license plate lights were out. I tried new bulbs, and when those didn't illuminate, I checked for voltage at the socket. Finding nothing, I hit the forums and found the many and varied threads on checking the wires in the rubber boot. When I took the interior panel off to look into the lock issue, I saw a connector that was unplugged. Plugged them together and guess what? I now have tag lights! I also saw other Christmas trees that were pulled out, so someone has been back there in the past. I guess they just forgot to plug the tag lights back in.
 
Last edited:

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
Check the wires up in the boot on the body side. There is possibly a grounding issue up there where the ground wire has a break in it. I had similar issues.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
I certainly plan on doing that since I have the panels off back there. It just seems odd that it works via the Tech II but no other way.

Strange beasts, these...
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
Here's how mine looks inside.



I was able to get it open by watching a video from Youtube. Here is a pretty clear one that has better close-ups than the one I watched.


This one shows how the window lock works with the main mechanism at the bottom.

 
Last edited:
  • Like
Reactions: mrrsm and Mooseman

C-ya

Original poster
Member
Aug 24, 2012
1,098
The last couple of days have been warmer than normal - we actually hit about 65F yesterday! My liftgate is not showing as being open and the lock is actually cycling with the rest of the doors via any of the means that the door locks cycle. Not sure what this means for troubleshooting except it seems more like the actual lock mechanism. Methinks some more cleaning is in order.
 

Sparky

Member
Dec 4, 2011
12,927
Water can get on the main latch mechanism from a sucked in gasket around the license plate insert (this is also a leading cause of liftgate rust). Mine is partially seized up again and I cannot open the glass, but the main latch remains fine so far. I've freed it up a couple of times but it ends up sticking after a couple months so I got tired of screwing with it.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
My license plate insert has a "resealed" gasket in it. I didn't find any water in the liftgate anywhere, nor any reals signs of it. It was rather dirty and some slight corrosion fuzz on the latch mechanism. I did notice while watching the window lock that it is not rotating completely back in line every time to allow the window to open.
 

Kurb

Member
May 3, 2014
89
I had problems with mine a few years ago. When I got it open, I sprayed some WD-40 on the latch, and I haven't had a problem since.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
I figured I should update this as I have come to a working resolution until the next failure happens. The major issue was the rear lock not locking and unlocking, and then it morphed into the truck telling the rear access was open, which inhibits the use of the rear wiper. I could make the wiper work by using my Tech II, but who wants to drive around with it plugged in all the time, right?

I took the plug off of the switch for closure indication and noticed it was dripping with some fluid. Not sure what it was as the rest of the area and assembly was dry. I blew it out with air and sprayed WD40 in the connector and into the socket on the unit. Next couple of days, all was good, then it started bonging at me that the rear access was open. Next stop, I pulled the plug and went about my way, figuring I would deal with whatever happened, and that it may hasten the purchasing of a new lock unit. But, the beauty thing is - nothing happened except everything works as normal now! The lock/unlock sound is very raspy, and it may still need to get replaced eventually, but for now, everything works. No false indication that the liftgate is open, and the wiper is always available for use.

20160405_130325_zpsimvzkg5p.jpg
 

Forum Statistics

Threads
23,271
Posts
637,476
Members
18,472
Latest member
MissCrutcher

Members Online