Adding a Blind Spot Monitor

Discussion in 'Clarity' started by MrFixit, Jul 15, 2021.

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  1. MrFixit

    MrFixit Well-Known Member

    Many of us were surprised that Honda did not include a blind spot monitoring system along with the other driver assist functions (some more useful than others). I am thinking of adding one, and would like to ask about any experiences you may have.

    First of all, please do not comment on reasons why it is not required. I am fully aware of the right-side rear-view camera. I am also well aware of other strategies like properly adjusting mirrors, and / or adding a small convex mirror (even though the diver's mirror already has the small section with a different orientation).

    I am interested in a high-performance / quality that can equal the performance obtained by factory OEM systems from Honda or other manufacturers.

    I have seen systems that are optical, or ultrasonic. These tend to be lower cost, and sometimes easier to install but from what I have read, they do not equal the performance of OEM systems both in terms of sensitivity and false alarms. Thus, I would like to focus on microwave (RADAR) systems which seem to be what the OEM manufacturers always utilize.

    The microwave systems are reasonably expensive, in the $400 to $900 range, just for the components.

    There is a thread in this forum discussing the Voxx ADVBSD20, where @CharlesBranch persistently tried to get it to work, but failed in the end. I have crossed that one off the list.

    A couple of others that seem to have good reviews are:
    1. The Brandmotion RDBS-1500. Apparently these are sourced by the same line as Toyota.
    2. The USASPEC BSM200. Very similar, with a nice adjustable bracket arrangement.

    Any of these microwave units are completely hidden and install behind the rear bumper cover. Removal of the bumper cover seems to be the most laborious part of the install.

    Does anyone have an opinion (or better yet, direct experience) with these two (or any other similar units)?
    Last edited: Jul 15, 2021
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  3. Teslawannabe

    Teslawannabe Active Member

    I have installed a microwave system along with the sonar system. You might as well do both while you have the bumper cover off, however nothing beats factory...of course anything beats Clarity not having any. I took a chance on a Chinese kit and I am very satisfied with it's performance, your milage my vary. I have three videos that are kind of broken down from the kit thru installation if you are interested.
    Sent from my SM-N986U using Inside EVs mobile app
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  4. MrFixit

    MrFixit Well-Known Member

    Sure... I would like to see the videos. Please post the links, or PM them to me.

    The installation angles for the RADAR transponders seem to vary some from maybe 25 degrees to 45 degrees.
    Was it pretty easy to find a location that didn't have to look through a sharp bend or discontinuity in the bumper cover?
    Were your sensors mounted to the vehicle, or glues to the inside of the bumper cover?

    I assume when you mentioned installing sonar too, that you mean parking sensors?
    I am not thrilled about drilling holes in the bumpers, plus, we rarely park in situations where it would be especially helpful.

    There are also some sonar-based BSM systems, but I don't imagine you would have doubled up on the blind spot function...
  5. Teslawannabe

    Teslawannabe Active Member

    I really need to consolidate these into one short video so please accept my apologies. Just scrub through them to see what you are interested in. The following was the first. I will follow up each in order. Like I said they are segments.

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  6. Teslawannabe

    Teslawannabe Active Member

    2nd video, I later decided to do both basically because I was there any way and it the inexpensive equipment failed maybe one of the two would still work.

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  8. Teslawannabe

    Teslawannabe Active Member

    Video #3. This was part of the installation of both kits.

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  9. Teslawannabe

    Teslawannabe Active Member

    Sorry, it looks so confusing, I posted on my own quotes lol.

    Final video showing systems working. Please note the beeper on the blind spot system failed right away, so led flashes but no beep. I find I prefer it that way.

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  10. Teslawannabe

    Teslawannabe Active Member

    There is a perfect spot in the corners for the radar and the bumper is even marked inside on where to drill for the proximity sensors. I, like you rarely ever see them in use ( or need them.) Once in a parking lot they went off from a pedestrian who quickly stepped behind the Clarity. On a side note: I didn't want to drill holes either, lol.
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  11. MrFixit

    MrFixit Well-Known Member

    Thanks for documenting your detailed experience with this ! Your videos are better than you give yourself credit for !

    I had actually already seen your videos in my travels while investigating this.
    Of course, I had no way to know that you were one of the forum members here..

    The microwave system you used is very definitely a bargain. It covers the main functionality that it is intended for.

    Most of the more expensive units also include some means to sense the vehicle's speed (either via the OBD2, or with it's own GPS receiver) in order to stop system operation below a certain threshold speed (like 20 mph). I believe this is to limit false detection's while driving around in a parking lot for instance. Have you found it to be annoying in a parking lot? Of course, if your beeper is disabled anyway, that lessens the annoyance factor for sure.

    This unit (and most others) has cross-track detection when you are in reverse. Do you have any comments on how well that works? The beeper may be more important here because you may not notice the lights when you are backing up...

    I find it interesting that all of these microwave systems have a shortcoming that seems fundamental. All of them cannot detect a vehicle that is squarely in the blind spot if there is no relative motion between you and the other vehicle. ie: If someone rides exactly in your blind spot and exactly matches your speed - no detection ! This seems like a 'fatal' flaw, but I think the reality is that it takes such little relative motion that this doesn't really occur from a practical standpoint.

    The only other thing that is available only with a few of the much more expensive units is 2-way detection. Your unit (and many others) theoretically only detects a vehicle that is overtaking you from behind. If you overtake another vehicle, and pass it, it will apparently not detect. Of course, if you are passing another vehicle, you will definitely be aware of it, so a warning is not as important. The scenario I think about is if you pass another vehicle, are not fully focused, and attempt to change lanes in front of the vehicle you just passed before you are really beyond it...

    Have you experienced either of these cases in your travels (not detecting someone stationary in your blind spot, or not detecting someone you have just passed)?

    It is tempting to try this low-cost system with the thought that it would be 'disposable' if I didn't like it. My only hesitation is that it is a fair amount of work, that I would hate to have to re-do again with another unit... Of course, spending more money does not guarantee that I would like it any better.
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  13. Teslawannabe

    Teslawannabe Active Member

    Thank you for your kind words. I try to present my experience and choice of the items I purchase with the goal of not trying to come across as a sales person (fan boy). I spend a lot of time commuting. Seeing many different traffic patterns on any given day. I also spend a lot of time around and in new vehicles with every kind of the latest technology. The BLIS/Cross traffic systems are great in new vehicles but not without false activations' such as backing out of a garage with obstacles, sometimes reported as cross traffic. The systems use a box/module called an SODML and an SODMR (brand specific called a side obstacle detection module right/left and this reports thru the network to the Body Control Module. The factory price is over $500 for one side, retail is much more and they do fail sometimes. During my research I found several systems that did in fact cost more then the one I chose. I did feel spending more money on a product would give me more confidence in that product. However several of the more expensive products had the same illustrations and looked the same (many Amazon venders sale the same products with different branding). So having said' that I did feel bad putting such an in expensive piece if hardware (both kits) on my vehicle. It is a lot of work as you have mentioned. I am very satisfied with my project outcome. It is just another tool to enhance safety. I find the best use of the system is when "THAT driver' who is weaving in and out of a smooth flowing traffic suddenly appears on your left finds out that lane is not moving quickly enough and then rolls over to the third lane and overtake' you on the right. Erratic traffic patterns and surprising vehicles from out of no where. That is when I am most pleased with the system. I hope this translates well from words to visualization. Please note: I was also looking for a project for my Clarity' so the labor was half fun and half work.
    Let me try to answer your questions and thank you for your patience as I try to put all this into words. 1."This seems like a 'fatal' flaw, but I think the reality is that it takes such little relative motion that this doesn't really occur from a practical standpoint." Most of the time it doesn't.
    2. "Have you experienced either of these cases in your travels (not detecting someone stationary in your blind spot, or not detecting someone you have just passed)? You have done your research well, the system does not cover that vehicle who wants to match your speed and hang in the blind spot and it does not help in passing a vehicle.
    You said it best...."Of course, if you are passing another vehicle, you will definitely be aware of it, so a warning is not as important."
    3. "Of course, spending more money does not guarantee that I would like it any better" This is so true.
    Hopefully this answers your questions. Please let me know if you have any more questions. These forums are great for information and I always try to do my due diligence before starting any projects.
  14. MrFixit

    MrFixit Well-Known Member

    Can you elaborate? I was under the impression that Honda did not have an OEM system for the Clarity.
    Did you dealer install an aftermarket system? If so, which one?
  15. MrFixit

    MrFixit Well-Known Member

    Correct me if I'm wrong... What you are describing (and had installed) are ultrasonic 'parking' sensors.
    This is completely different than blind-spot detection which senses someone at highway speed as the enter into your blind spot(s).
    Blind spot detectors are microwave and are installed behind the bumper cover, and thus are not visible outside the vehicle.
  16. MrFixit

    MrFixit Well-Known Member

    Videos showed install for both.
  17. MrFixit

    MrFixit Well-Known Member

    I decided to go ahead with installation of a Blind Spot Monitoring (BSM) system. After researching alternatives I chose to use the system from USA Spec (Model BSM 200). This is a microwave radar system with two sensors installed in the rear (angled at +/- 45 degrees), underneath the plastic bumper cover. It's functions include 2-way blind-spot detection and warning (both when you are being passed, or when you are passing another vehicle), and rear cross-traffic detection (when in reverse). My #2 candidate was the RDBS-1500 made by 'Brandmotion'.

    These systems are reasonable expensive, say $500 to $1000 just for the parts. You can find some low cost versions on Amazon (maybe as low as $100), but they generally lack some element of performance and I would be worried about quality. Knowing the scope of the installation effort, I decided on a 'better' unit, hoping for better quality and performance. I do acknowledge that paying more does not insure better quality!

    The USA Spec lists (and typically sells for) $830, but I found a good price at CarID selling for $520. If you had this, or a similar system installed professionally, you would expect to pay at least $1000 because it is pretty laborious.


    Most of these units use vehicle speed, and operate when the vehicle speed is over 18-20 mph. This one uses the OBD2 connector for that purpose. There can be incompatibilities with some vehicles with detecting speed, but experience has shown that this one works fine with the Clarity. As an alternative, other models have their own built-in GPS receivers to measure vehicle speed.

    In addition to the two rear sensors, there is a control unit that mounts in front (usually under the dash), two indicator lights (left and right), and a warning beeper. There is a cable harness that must be run from the rear sensors to the front where the control unit and indicators are. Connections to the vehicle include 12V power, left and right turn signals, backup light, and the OBD2 connector.

    There is a test procedure that you can do prior to installation that verifies system operation and OBD2 compatibility.

    In summary, the installation procedure is this:
    1. Identify location for sensors
    2. Remove the rear bumper cover
    3. Remove trunk liners (or loosen and bend aside) for access to tail light and path to feed cable harness forward
    4. Mount radar sensors at identified locations with the included brackets at the proper position and angle
    5. Remove plastic panels in cabin for access to door sil plate and B-pillar areas to allow routing of cable to front of vehicle
    6. Fish cable from trunk to cabin (I could do this without removing the rear seat).
    7. Tap into and wire to left and right turn signals at respective tail light
    8. Tap into and wire to backup light in trunk lid area (more on this later).
    9. Remove left kick panel, near hood release, providing access to mount control unit and wiring connections.
    10. Mount control box under dash, indicators, and beeper in cabin
    11. Route and connect cabling.
    12. Put it all back together again !

    A warning - This job is not for the faint of heart. Although not technically difficult, it is laborious and time consuming. I had read that a professional install would take maybe 4-5 hours. I am pretty meticulous, but it took me twice that amount of time (a full day). I did not have any 'problems' along the way, it is just laborious.

    I won't present all the bloody details of the installation other than providing some photos for reference.

    Removing the rear bumper cover is fairly involved, but there is an EXCELLENT procedure presented by Russell Wright here:

    A note about sensor position - The sensors look through the plastic bumper. There needs to be no metal in this area (not a problem). But also, you do not want the sensor to look through a complicated plastic shape with a sharp bend or 'pattern' of any kind. The fake plastic vents would not be a good location.

    Here are the areas I considered, and ultimately selected:



    Here are the sensors after mounting:

    DSC04545 & 46_email.jpg

    Tapping into the taillights for L and R turn signals:
    Rear view of taillight area showing connection to turn signals (left view shows where I tapped the backup light from that harness):



    These are the Color codes for the tail light connections:

    GND - Black
    Turn - Grey / Blue Tracer
    Brake - Green
    Tail - Red

    GND - Black
    Turn - Grey / Brown Tracer
    Brake - Grey / Green Tracer
    Tail - Grey / Red Tracer

    Tapping into the backup light was a challenge. The backup lights are in the trunk lid. I could not figure out how to gain access to the wiring inside the trunk lid, nor did I want to route this wire through the flexible harness that hinges with the lid. I cut the harnass open near the left taillight, and found 15 wires running to the lid! I have no idea what all of them are for, but I was able to identify which was the backup light by using a clamp-on DC meter to find which one had current when just the backup light was on. It was a white wire (unfortunately there are 3 identical white wires so I can't tell you which one is 'right'). In any event, I spliced into that wire to access the backup signal for the BSM.

    In the front, here are the indicators (they are surface-mount, so no need to remove the A-pillar coverings). They are self-adhesive but they would not stick to the plastic because it is curved. I used some adhesive Velcro, and it remains to be seen if they will hold over time. If this doesn't work, I may try a dab of RTV.


    Here is the under-dash are where I mounted the control box (next to the fuse block). This also shows the OBD2 connection and the way that I tapped power from the empty accessory fuse location (Fuse #2). All excess cable lengths and the control box are zip-tied in position.


    The beeper is just zip-tied to an air vent under the dash (not shown).

    The corresponding warning light illuminates when another vehicle enters your blind spot (assuming your speed is at least 20 mph). If you activate your turn signal while another vehicle is in your blind spot, then the beeper warns you. For the cross-traffic alert, it works when you are in reverse (hence the connection to the backup light). If a vehicle approaches you from with either side while you are in reverse, the corresponding indicator will illuminate, and you get a warning beep.

    During my first test drive, I discovered that I got no warning beep with a blind spot on the right when engaging the turn signal. I quickly found that my tap into the right turn signal did not pierce the insulation so the control box got no right signal message. It was simply a matter of re-doing that tap.

    I do not have much experience with this system yet, other then the initial test drive, but it seems to be functioning properly. I will report back later as I gain more experience with it.
    Last edited: Aug 4, 2021
  18. insightman

    insightman Well-Known Member Subscriber

    An excellent report! Thanks for your meticulous and interesting description of your project. I look forward to hearing about your experience with the system you selected. You are one of the reasons this forum is so great.
  19. Teslawannabe

    Teslawannabe Active Member

    Great install and very detailed. Thanks for sharing installation.
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  20. MrFixit

    MrFixit Well-Known Member

    I wanted to report back after gaining some experience with the BSM-200.

    I really like the blind-spot detection, and I feel like it works as well as the OEM systems that I have seen in other vehicles. It detects a vehicle prior ro entering the blind spot(s) both when you are being passed on either side, and when you are passing another vehicle. It seems to limit it's detections to the adjacent lane as expected (ie: I have not seen false detections from a vehicle that is 2 lanes over).

    With the rear cross-traffic alert function (engages when you are in reverse), there are circumstances where it gives false warnings. When you are parked between 2 cars, I do not tend to get false warnings, but if there is an empty spot next to you, and then a car, it tends to alert when you begin to move. I think when it sees some relative motion in this mode, it can't really tell whether you are moving and its looking at a stationary object, or whether you are stationary and it is looking at a moving object. This false alert can also occur with a light post or similar stationary object when you start to move depending on the geometry. It does alert when it is supposed to (for instance, when you are sneaking out of a parking spot and you cant see well).

    All-in-all, I definitely like the blind-spot alert, and have some mixed feelings about the rear cross-traffic function.

    I have not has any prior experience with either of these functions before installation on the Clarity, so I would welcome any thoughts from those who may have these features as standard, or options on other vehicles you may own...
    KentJohnson and Teslawannabe like this.

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