2005 V70 Tailgate Open Warning Light

[tecljc4]

I can't get rid of the open tailgate warning light even though it is shut firmly. It also means the lock/alarm doesn't work quite right as well. Any ideas on how to resolve this? ThanksQ!

[chrism]

There are two possible reasons for the tailgate open warning that come to mind - probably more possibilities that I'm not aware of.

One possibility is that the sensor switch on latch is not opening/closing as it should. You have to remove the inner hatch trim panel to access the latch and test its function.

Another possibility, and quite common on the wagons, is the severing or shorting of the tailgate wire harness where it exits the car body at the LH tailgate hinge. I shared my experience a couple years ago on this forum:

https://www.matthewsvolvosite.com/forums ... =9&t=47882

[Ryann]

After way too much work, I just fixed this on my 03 V70 and I thought I'd share in more detail what my problem and solution was. If I had read this, it would have saved me a ton of work and grief. This may also apply to the XC70 and XC90.

Background:
The circuit for the tailgate open sensor passes through the latch, then through the rear glass breakage detection sensor, then to ground (which it shares with the rear defroster).

Access
If you take the trim off of the inside of the rear hatch, you will see two wires attach to the rear window on the left side. The big red one is defrost, the small one is glass breakage. On the right side there's just one large black wire. This should be ground.

Testing
Test the ground at this thick black wire. I used the rear 12v outlet, but you could go direct to the battery if you want to take some things apart.
If you have ground here, your harness may be ok.
When I tested resistance between the glass breakage sensor (small wire to glass on left side) and ground (large black wire to glass on right side) I had 800 ohms which is much too high. I've also heard of these wires becoming broken or otherwise mechanically detached from the window.

Solution
My solution was to run a small wire from the glass breakage sensor (small wire to glass on left side) down around the bottom of the rear windows to the ground (large black wire to glass on right side). This bypasses the glass breakage sensor. Very easy and I don't really care if my alarm doesn't go off if my rear window is broken.

Hope this helps someone.

[- Pete -]

Usually it’s the big black ground wire has busted as seen below, left side tailgate hinge area. I tried to read Ryann’s post but didn’t make it through.

Make sure after you put in a new section of wire that the bundle is routed correctly. Improper routing is why these break in the first place. Pretty easy to figure out how it needs to be routed for proper flexsion.

If your tailgate struts are feeling flaccid or have lost their damping now is a good time to replace them.

[Ryann]

I spent a long time and a lot of effort looking for a broken wire at the hinge (as in your picture). I just wanted people to know that this isn't always the problem, and sometimes the solution is much easier.

I also wanted people to know that they can check the integrity of the "big black wire" by checking for continuity between the right side of the rear window (defroster) and chassis ground

[plumsmooth]

My Tailgate open warning started malfunctioning after a load of messy dirt/sand went in there for my Driveway. One benifit of a 22 year old Volvo Truck with a Cap: V70 2004 Wagon! I cleaned out the latch area and it worked temporarily but now is malfunctioning again...