Rear Camera Seemingly Causing Interference With Key Fobs

[kbpark824]

Hello,

I recently bought two Viofo A129s and installed both of them - one on a 2017 BMW X3 and one on a 2010 Lexus ES350. Both dashcams are hardwired to non-switched fuses for around-the-clock recording.
As soon as I installed both dashcams, the key fobs began behaving oddly on BOTH cars. This behavior includes:

- Car not unlocking/locking when using the fob from anywhere outside of ~5 ft of the car
- Car not detecting the key fob when inside the car, therefore preventing the engine start/stop from working

Naturally, I initially thought to replace the batteries in both key fobs. That did not solve the problem. The next step was to disable WiFi on the cameras, as I though they may be causing interference. The issue persisted. Next, I unplugged both cameras to turn them off, and that brought normal functionality back to both key fobs.

To further isolate the issue, I plugged the cameras back in, but removed the cable that goes to the rear camera (I removed the end that is plugged into the front camera). That made the key fobs work correctly!

Just to ensure that I had identified the problem area correctly, I plugged the rear camera back in, and the key fobs stopped working again!

Has anyone ran into this issue? I thought the rear cable may not be well shielded/insulated, so I contacted the seller on Amazon, but they are claiming that this is not the case and that the cable must be good quality because it's thick (since when do thick cables mean 'good' cables?).

Anyhow, I could be wrong and it might not be the cable, so I thought I'd see if anyone else may have experienced this issue.

Thanks in advance!

 

[DarthMaul]

I don't know how can that be fixed, but, if that's not too much work, I would run the rear camera cable through the other side of the car.

 

[kbpark824]

I just spent the last few hours doing this on the Lexus. Same problem. However, if I let the cable in the rear just hang, the key fob works. When I tuck the cable into the headliner, the key fob stops working again. Very strange. Maybe the key fob receiver is in that area of the headliner. If that is the case, then it must be the cable causing interference, correct?

And if that's the case, it DOES seem like the cable has terrible shielding/insulation.

 

[CaptureYourAction]

Cut open a A129 rear cable to check out the shielding (cable was already damaged). It's double shielded with foil and braid. Not a shielding expert so can't comment on the quality of the shielding though.

Maybe the fob receivers are near the rear camera mount location?

 

[jokiin]

I just spent the last few hours doing this on the Lexus. Same problem. However, if I let the cable in the rear just hang, the key fob works. When I tuck the cable into the headliner, the key fob stops working again. Very strange. Maybe the key fob receiver is in that area of the headliner. If that is the case, then it must be the cable causing interference, correct?

And if that's the case, it DOES seem like the cable has terrible shielding/insulation.

you're correct that the cable has terrible shielding however it's not the camera cable that has terrible shielding, it's the key fob receiver antenna that has terrible shielding, it's designed to pickup a signal from a very low power transmitter (the key fob) so it's like that by design, the vehicle manufacturer (rightly so) doesn't make any allowance for other electrical devices that you may place nearby so they see no need to shield the antenna, shielding it would reduce its performance anyway

moving the cable away and leaving it hanging shows that the cable position is an issue so you may be able to move the rear camera cable to the opposite side of the vehicle roof, or run it down the floor and back up to avoid the problem

 

[borik]

moving the cable away and leaving it hanging shows that the cable position is an issue so you may be able to move the rear camera cable to the opposite side of the vehicle roof, or run it down the floor and back up to avoid the problem

or take aluminum foil (double / triple) and tape it around the cable to add more insulation.
if you already routed the cable on the passenger's side.

 

[jokiin]

it's double shielded already so it may have some minimal effect to wrap it further, moving it away from the antenna for the fob would likely still be needed, the antennas for those things are quite sensitive

 

[borik]

it's double shielded already so it may have some minimal effect to wrap it further, moving it away from the antenna for the fob would likely still be needed, the antennas for those things are quite sensitive

seems like we have to insulate more just one of two things - the antenna or the camera's wire.
in any case it should prevent the interference between both.
I made once (just for a test) a wallet like made of an aluminum foil to prevent the key fob sensing the car. it worked. but after a month or two (I kept the spare key in that "wallet") I tried to use it and found out it works in less than 50% when I try to start the engine. I can lock / unlock the doors using a remote just fine but not to start the engine.

 

[DarthMaul]

How about running the cable at the floor level? It shouldn't cause any interference anymore.

 

[borik]

How about running the cable at the floor level? It shouldn't cause any interference anymore.

it would work if the cable is long enough to reach the rear camera.

 

[jokiin]

seems like we have to insulate more just one of two things - the antenna or the camera's wire.
in any case it should prevent the interference between both.
.

shielding helps but it's not a cure all, shielding the antenna would reduce its ability to operate as intended, the antenna is intended to receive signals, it will receive good and bad equally well, moving the cables away from each other is likely going to be required regardless

 

[borik]

shielding helps but it's not a cure all, shielding the antenna would reduce its ability to operate as intended, the antenna is intended to receive signals, it will receive good and bad equally well, moving the cables away from each other is likely going to be required regardless

if / when I get A129 Duo I will let you know what at least I tried to solve this problem.

 

[kbpark824]

Thank you all for your replies. Just to clarify some things:

*Note: All the information below pertains to the 2010 Lexus ES350
1. I initially ran the cable for the rear camera along the driver's side of the car, on the top.
2. This morning, I re-ran the cable along the top, but this time on the passenger side.
3. The key fob still didn't work properly, so I ran the cable on the passenger side, but this time along the bottom. I then ran the cable up from the bottom through the C pillar.
4. While I ran the cable from the bottom through the C pillar, I noticed that the smart key receiver is actually located at the top of the C pillar.

Now, when I try to tuck the cable between the C pillar and the rear camera into the headliner, the key fob stops working. When I pull out the cable I tucked in and let it hang between the C pillar and the rear camera, the key fobs work fine.
My guess is that there is a wire (maybe an antenna) that runs from the smart key receiver through the headliner in the rear. I'm going to try running the cable along the bottom of the rear windshield tomorrow and see if that resolves my issue. It will not be as pretty as having all the cables tucked away, but at least the key fob will work.

I'll let you all know if that fixes my issue, and I'll update the thread on how I end up resolving the issue with the BMW X3, if I do.

In the meantime, if anyone has any other ideas, or if anyone can shed some light on how I might solve the issue with either car specifically, please let me know

 

[jokiin]

if you need to cross the path of the antenna keep the cables at 90 degrees to each other rather than running them alongside each other

 

[borik]

4. While I ran the cable from the bottom through the C pillar, I noticed that the smart key receiver is actually located at the top of the C pillar.

you may try to find the exact locations of all the smart key receiver locations and try to isolate or block one of them that cause the problem for a cable and check if the smart key receiver still works without one location or run a cable around it.

 

[NomadTech]

double shielded already

But is the shield connected to ground? If not, that's the problem

 

[jokiin]

Faulty cable is a possibility, have seen this issue often enough to suspect that this will be an issue regardless

 

[kbpark824]

Hey all, just a quick update for anyone that may be dealing with similar issues. I was able to resolve this issue with both cars.

- For the Lexus ES350, the way I routed the cable ended up being the reason for the key fob interference. The receiver for the key fob was in the right-side C-pillar, and there was a wire (I'm thinking an antennae) that extended from the receiver, across the headliner (perpendicular to the C-pillar). I had to lower the mounting position of the rear camera, and keep the rear camera cable away from the headliner. Unfortunately, this meant that I had to sacrifice aesthetics, but I did the best I could with cable ties, etc., and it ended up not being that bad.

- For the BMW X3, there wasn't anything in the pillars causing the interference, but something near the top-rear of the car. I think it may have been the wiring that goes to the roof-mounted antennae. I had to lower the mounting position of the rear camera, and that did it.

Now the cameras work, AND the key fobs work

 

[Mike Smith]

I've not had any issues with my 2013 BMW 3 series

 

[hrothgar]

Made an account just to add to this. I have the same dash cam. 2014 Lexus GS350. Dash cam on passenger side of the rear view mirror. Power coming from Driver’s side wire loom. Rear camera wires run down a pillar behind side curtain airbag down to the floor and in between carpet then back up rear seat to headliner to camera. I have issues with key fob range and delay if there is power to the camera. Doing research now to figure out how to resolve this.

I am going to look around and see if i can reroute away from the C pillar like OP and further confirm.