Installed a Draw-Tite Hitch (for bikes), now my "Kick to Open Hatch" is impaired.

[dhoerl]

I spent the weekend installing the hitch - plan to post what I learned (with photos) soon. But after finishing up and driving the car somewhere, I find that I can't kick to open the hatch now. Amazingly it had been working flawlessly!

I googled a bit but can't find any info on what the technology is that opens the hatch. Obviously the metal hitch is interfering with it, and I am probably going to need to move the sensor if possible.

Hopefully this feature won't be lost forever.

Surprisingly I didn't see any comment on this anywhere. I'm also pretty sure I didn't disconnect a wire but who knows.

Would be most appreciative if someone can shed some light on this!

Sponsored

 

[SnBGC]

Maybe this will help.

Power Liftgate Hands-Free Feature

In addition to the passive entry system, the power liftgate hands-free feature utilizes a module and 2 capacitive sensors (located behind the rear bumper cover) for operation. The BCM sends a voltage signal to the hands-free liftgate actuation module. The hands-free liftgate actuation module monitors the 2 sensors. When the correct motion is detected (forward and back such as a kicking motion under the rear bumper), the hands-free liftgate actuation module communicates to the BCM via a LIN. The LIN supports bi-directional communication between the hands-free liftgate actuation module and BCM, allowing the liftgate passive entry process to begin (as though the liftgate release button was pressed)

Hands-free liftgate DTC is set in the BCM, if any failure occurs over the LIN.

The BCM verifies a valid programmed Phone as a Key within range of the rear keyless entry antenna and sends a message to the RGTM to open the liftgate.

The 2 capacitive hands-free liftgate actuation sensors are serviced as a single assembly

 

[dhoerl]

Maybe this will help.

Power Liftgate Hands-Free Feature

In addition to the passive entry system, the power liftgate hands-free feature utilizes a module and 2 capacitive sensors (located behind the rear bumper cover) for operation. The BCM sends a voltage signal to the hands-free liftgate actuation module. The hands-free liftgate actuation module monitors the 2 sensors. When the correct motion is detected (forward and back such as a kicking motion under the rear bumper), the hands-free liftgate actuation module communicates to the BCM via a LIN. The LIN supports bi-directional communication between the hands-free liftgate actuation module and BCM, allowing the liftgate passive entry process to begin (as though the liftgate release button was pressed)

Hands-free liftgate DTC is set in the BCM, if any failure occurs over the LIN.

The BCM verifies a valid programmed Phone as a Key within range of the rear keyless entry antenna and sends a message to the RGTM to open the liftgate.

The 2 capacitive hands-free liftgate actuation sensors are serviced as a single assembly

Curious where you got this - is there a Service Manual that mere owners can get?

 

[SnBGC]

Curious where you got this - is there a Service Manual that mere owners can get?

Comes from the Work Shop Manual. I believe anyone can have access for a fee ranging from reasonable or a few days to highway robbery for annual subscriptions.

I found the info in section 5: Body and Paint. Sub Section 01 -03 Body Closures.
Top view is Component Locations. The text was copied and pasted from System Operation and Components.

 

[dhoerl]

Given that I now know where the sensors are, I tried again - and am having some success. The trick it to kick at a slight angle so your ankle hits the chain loops.

First I tried the left side, had a few successes when I actually touched the hitch, then was able to get it going on the right too.

So - it looks like the hitch impairs the action - it use to work first time with either a kick or a swipe left or right. Now I need to find the "sweet spot" and may need a few attempts.

 

[dhoerl]

I don't know how difficult it would be to move the wires to one side - if someone else does this install might be worth thinking about.

 

[MYOUTH]

I don't know how difficult it would be to move the wires to one side - if someone else does this install might be worth thinking about.

How’s the Drawtite hitch working out? Pictures please.

 

[JeffGo]

This is not a unique problem to the MME. Honda CR-V, for example. My wife's CR-V doesn't have a kick to open, so not a problem for our bike racks. But it does give me pause about adding the hitch to my MME.

 

[dhoerl]

How’s the Drawtite hitch working out? Pictures please.

Will do a post with photos and tips shortly - but there is already one for this hitch (that I just tripped over) "Draw-tite Trailer Hitch Receiver Install"

 

[Mach-Lee]

Yes, there is a capacitive sensor (#4) in the bumper that monitors the electric field around it. When it detects a conductive object (your leg) moving closer and away in a specific pattern it opens the trunk. Putting a metal hitch in front of it blocks some of its ability to sense field changes, similar to how metal blocks radio waves.

On other Fords that have factory hitches, there is a separate RGTM calibration that compensates the sensing for the effects of the hitch. They may also have a different sensor wire arrangement. Unless they have factory hitches in Europe, I don't think this alternate calibration would exist for the Mach-E. You'd just have to live with the reduced sensitivity.

 

[dhoerl]

Documented my install: My Draw-Tite Installation (note the other one I had posted earlier: Draw-tite Trailer Hitch Receiver Install)

 

[TargaGone]

I found a Texas Instruments treatise of these sensor systems - 20+ pages

Pertinent to hitches:

The capacitive sensing solution is affected by nearby conductive metals. Figure 29 shows the effect of placing a 5 kg piece of steel (a bench vise) right next to the capacitive antenna. In this case, the 5 kg piece of steel was not grounded, but was simply placed on the plastic bumper cover on which the antennas are mounted. There is a shift of in the background measurements from about 33.17 million counts to about 32.92 million counts, or a shift of about 250,000 counts, or about 0.75% of the original measurement. Compared to the measurements during a kick gesture, this shift is very significant, at least 10 times larger than the standard kick measurement amplitude. However, the measurements for the kick gestures, three before the steel was added, and three kicks after the steel was added, appear to show similar response in terms of the amplitude of the measurements during the kicking gesture. This indicates that while the introduction of metal close to the antennas causes a shift in the measurements, the sensitivity of the system to kicking gestures is not significantly impacted.

Open the doc for graphs etc. Pg 22 for sensor test placement.

 

[Mach-Lee]

I found a Texas Instruments treatise of these sensor systems - 20+ pages

Pertinent to hitches:
Open the doc for graphs etc. Pg 22 for sensor test placement.

Thanks for finding that, I fixed the link: https://www.ti.com/lit/ug/tidud21/tidud21.pdf

I got a "kick" out of their kicking machine for testing. ?

This is a great read for those interested in how the system works. A metal object nearby won't affect the sensitivity as long as it's not electrically connected to the sensor ground. Grounding the object to the sensor reduced the kick sensitivity to 1/3 of the original, which makes sense because it would become electrically part of the "antenna" and affect the field distribution in a bad way. It's not clear if the actual implementation on the Mach-E isolates the sensor ground from the body ground or not, but the reduction in sensitivity seems to suggest it would be connected.

The other take-home message here is that kicking as close as you can to the sensor will improve the detection. You will probably have to get much closer than before the hitch was on for it to work.

 

[TargaGone]

Also - a wire in your shoe increases kick effectiveness by many fold.

 

[TargaGone]

I installed a Draw Tite hitch yesterday (MME was brought home on 12/30) and wanted to preserve full function of the kick sensor. I love magic stuff. Below are pictures of the stock location of the sensors and where I moved them to - over the Driver side exhaust pipe - sort of . I used double stick foam tape I had purchased for a window pane install.

Observations - the stock sensors are well away from the cutout needed to install the hitch. 250 miles is enough to dirty the underside of the pristine new car.
The hatch did open once when I walked past the left rear bumper. I thought I matched the position height of the stock placement. I may need to move the lower antennae further under the bumper.

Installation tip. The One Up being attached helped balance out the rig for raising with the jack.