Reverse parking sensors – false alarms

[BobB]

At the time of purchasing my NC Roadster Coupe, the dealer installed Mazda reverse parking sensors. Ever since installation, they always false alarm on coarse-chip surfaces. There is no problem on smooth surfaces.

The dealer replaced the control module, then the sensors, then the rear bumper (because they said they used the template for a soft-top instead of a retractable hard-top). All to no avail.

The dealer has been helpful but we appear to have run out of options

Has anyone had this problem or offer any suggestions?

[Okibi]

Nice to see the dealer was trying to fix the problem rather than ignoring the issue.

[Benny]

Perhaps when they fitted them, the sensors were installed incorrectly.
The sensors have an specific angle of \"vision\" and if turned upside down, will read the road instead of what is directly above them.

I have them on my Merc (factory fitted), and every now an again, they will false alarm, especially if it is raining hard, however, they do give you an off switch.
They also switch off above about 10km/h and automaticaly switch back on as you slow down.
When you are stopped at traffic lights, pedestrians who walk close to the car will also set them off.

You can ask the dealer to wire them so that they will only work with the car in reverse gear, so that should help a little.

[Mr Morlock]

What you have here is the classic case of problem solving- the dealer does not know the root cause and goes about replacing bits and pieces in an effort to solve it. Certainly I do not know the cause but one of the first things to establish is whether the unit that was sold is compatible with your car. The dealer should have a network to determine if it is specifically recommended and successfully trialled. If it were say a Ford you would not buy an accessory for a particular model which the engineers had not assessed and which was not functional and safe. I had a Bosch park pilot fitted on a vehicle ( 4 sensors) and have had no problems- this unit works only on reverse and can be switched off when say towing a trailer.

[TieNN89]

Can you take pictures of the sensors installed one of the back

and a side picture of the sensors

Do you have a towbar?

I have them on my Merc (factory fitted), and every now an again, they will false alarm, especially if it is raining hard, however, they do give you an off switch.
They also switch off above about 10km/h and automaticaly switch back on as you slow down.
When you are stopped at traffic lights, pedestrians who walk close to the car will also set them off.

You can ask the dealer to wire them so that they will only work with the car in reverse gear, so that should help a little.

mmm yours must have costed a lot

thats how they are usually hooked up only works when in reverse
I know this is how the Mazda 3s are hooked up (genuine accessories)

Certainly I do not know the cause but one of the first things to establish is whether the unit that was sold is compatible with your car. The dealer should have a network to determine if it is specifically recommended and successfully trialled. If it were say a Ford you would not buy an accessory for a particular model which the engineers had not assessed and which was not functional and safe. I had a Bosch park pilot fitted on a vehicle ( 4 sensors) and have had no problems- this unit works only on reverse and can be switched off when say towing a trailer.

Thats not the case

I can fit reversing sensors to most cars you want as long as i can drill 21mm holes into your bump

It should work.

The sensitivity of the reversing sensors could be up too high most can't be adjusted as its the way its made

[BobB]

In response to your replies, the reverse parking sensors are a genuine Mazda MX-5 accessory, which I ordered with the car and were dealer fitted pre-delivery. See here: http://www.mazda.com.au/Models/Current% ... ories.aspx

But this is the interesting point; I have just noticed on the Mazda web site picture that the sensors are mounted at the top of the bumper, whereas mine are mounted in the middle of the bumper, in line with the towing point.

Surely if mine are 8cm or so closer to the road than they should be, they would be over-sensitive. And this is after the dealer has already replaced the whole bumper because they say they used the wrong template the first time round.

The car’s going back on Monday.

Can anyone with a NC Roadster Coupe with Mazda reverse sensors confirm that the location of theirs matches the pic on the Mazda web site?

[Mr Morlock]

BobB- looks like you have done things the right way and the dealer is obliged to rectify it. It makes sense to me the position of the mount has a bearing on the performance. The 5 is low to the ground and the sensors will certainly activate if the ground comes within the range of the unit. My car ( not my 5) with the Bosch unit has a high ground clearance but if you back it against a steep slope it activates. My unit starts beeping at 150cm with continuous tone from 30cm.

[TieNN89]

But this is the interesting point; I have just noticed on the Mazda web site picture that the sensors are mounted at the top of the bumper, whereas mine are mounted in the middle of the bumper, in line with the towing point.

as i dont have an NC could you also measure how high off the ground those sensors are?

and

Can you take pictures of your sensors installed

pictures of the rear of the car
and side pictures of the sensors

Do you have a towbar?

[BobB]

AZNTieN, I don’t have a tow bar.

I can’t organise a pic right now but my sensors look exactly as shown on the link I provided, : http://www.mazda.com.au/Models/Current% ... ories.aspx or,
http://www.centenary.com.au/mazda/acces ... X5_Acc.pdf or the UK site, http://www.mazda.co.uk/Showroom/MX-5/MX ... cessories/

My sensors are located 48cm off the ground – looking at the web site picture they should be around 56cm off the ground.

Looks like the dealer will have the replace the bumper a second time. A pity, as I didn’t have a single blemish on either of the two rear bumpers.

[TieNN89]

just incase you were wondering why i ask these sorta questions

its because i fit these things at work

actually i fitted one today on a ute

anyway sounds like its a bit low

on some sensors there a top

the newly updated ones we got now don't have a top tho

If you look at your sensors on the side does the sensor go like this / (obviously not that much of an angle) with the sensor slightly facing down if so it should be like this |

I'm not sure with the genuine ones but the ones we fit at work they come with angle rings which makes the sensors sit like this |

[BobB]

AZNTieN, I’ve just had a very close look and the sensors seem to be sitting very uniformly and there are no marking signs (not on the outside anyway).

I’m just sorry I didn’t look at the MX-5 accessories brochure months earlier and notice the higher location shown on the brochure.

I will take my accessories brochure to the dealer on Monday.

[TieNN89]

AZNTieN, I’ve just had a very close look and the sensors seem to be sitting very uniformly and there are no marking signs (not on the outside anyway).

I’m just sorry I didn’t look at the MX-5 accessories brochure months earlier and notice the higher location shown on the brochure.

I will take my accessories brochure to the dealer on Monday.

the marking would be on the back of the sensor (behind the bumper)

yeah take it back to Mazda and show them the brochure

unfortunately i've never fitted a genuine Mazda one or on an Mx-5 so can't really say whether its high or low but 48cm doesn't sound low

I'll measure up the ones i just installed today

[BobB]

AZNTieN, I assume you install generic sensors. If so, they wouldn’t come with a template for a specific vehicle so how do you determine the optimum placement on the rear bumpers?

Cars have different bumper heights and I am thinking that if the distance to the road is too close, they will be over-sensitive.

[BobB]

Problem cured. No further problems.

I contacted Mazda Australia who contacted the dealer.

All that was required apparently was to open the control module and adjust the sensitivity.

Over months, in an attempt to cure the problem, the dealer replaced the module, the sensors and even fitted a new rear bumper (which they had to spray paint because they come unpainted, as do the sensors) and repositioned the sensors.

Makes you wonder how they make a profit.

[Okibi]

Glad to see they're fixed, coming along to the MX-5 club run on the 1st Sunday of the month?

www.mx5club.com.au