• Welcome to Mazdas247, the 24/7 Mazda Community and Resource. Learn about the benefits of becoming a Member here.
  • We're an Amazon Associate and eBay Partner. We earn from qualifying purchases.

Mazda cx5 emergency braking when reversing a trailer

We've had a tow ball on the car since we bought it and it was the first time reversing the car the other day with a trailer and it would lock up the brakes and flash emergency brake on the heads up display. Is there some trick to turning this off or should it already know this when you plug the trailer lights switch in????
 
:
Pueblo county CO
:
CX-5 Sport 16.5 6M
Huh? Were you able to reverse?
Could it be the Hill Holder?

Sounds like a major inconvenience.

Did you use any kind of 4-7 pin adapter?
Does this trailer have trailer brakes?

I haven't use my hitch to tow, only hitch mount accessories but I would like to be able to tow and backing up is difficult enough.
 
:
2019 Mazda CX-5 Signature
All good questions, I'll add:
Is it actually applying the brakes, or is it telling you to "BRAKE!" in the display?
Was this a factory installed hitch/harness?
If not, what brand harness/adapter was used?
Does it do this if you temporarily disconnect the trailer light connector?

It is also possible the trailer is being detected as an obstruction by the rear sensors. In that case you'll need to turn-off that feature. Check the manual.
 
Last edited:
:
Southwest Ohio
:
'19 CX-5 diesel
Turn off the parking sensors (by left knee. Button is illuminated with Amber when on)
 
Turn off the parking sensors (by left knee. Button is illuminated with Amber when on)
I tried that and it stops the sensors beeping and turns off the display with the picture of the car with the red lines when you get close to something. But still just locks up the brakes to try to stop a collision.
 
Huh? Were you able to reverse?
Could it be the Hill Holder?

Sounds like a major inconvenience.

Did you use any kind of 4-7 pin adapter?
Does this trailer have trailer brakes?

I haven't use my hitch to tow, only hitch mount accessories but I would like to be able to tow and backing up is difficult enough.
I was able to reverse at like o.5km/h looking like an idiot at the boat jetty and with a couple of full wheel lock-ups as a bonus. The trailer has no trailer brake because it's a small tinny but it has a 7 pin plug for the lights.
 
All good questions, I'll add:
Is it actually applying the brakes, or is it telling you to "BRAKE!" in the display?
Was this a factory installed hitch/harness?
If not, what brand harness/adapter was used?
Does it do this if you temporarily disconnect the trailer light connector?

It is also possible the trailer is being detected as an obstruction by the rear sensors. In that case you'll need to turn-off that feature. Check the manual.
yea just pulls the brake pedal down and lock up the brakes and yes factory hitch and harness bought it brand new with the car. It is detecting an obstruction by the rear sensors but when you turn off them by the button it stops the beeping and everything but still just locks up the brakes
 
:
Pueblo county CO
:
CX-5 Sport 16.5 6M
Wow. You would think the factory setup should work ok. Were there special towing instructions included? I know the manual has info on towing but I haven't read all of it.

What about the dealer? Have you asked them? Sounds like a possible software glitch. Maybe they have some trick or patch.
 
:
Southwest Ohio
:
'19 CX-5 diesel
When I tow, I turn off the "parking sensors" with the left knee button and also turn off the "Blind Spot Monitoring System (BSMS)" via the entertainment screen. Have not had any issues. Aftermarket hitch & T-connector wiring self installed.

If it's not one of those two systems causing your problem, you could try turning off the "Smart City Brake Support" ( SCBS) although I don't think that is the problem. Beyond that, I don't have an idea for you.
 
Last edited:
From a Jeep forum with the same issue...

"Oh, yes. Problem was solved by dealer replacing of the rear emergency braking backup assist module."
 
:
2019 Mazda CX-5 Signature
yea just pulls the brake pedal down and lock up the brakes and yes factory hitch and harness bought it brand new with the car. It is detecting an obstruction by the rear sensors but when you turn off them by the button it stops the beeping and everything but still just locks up the brakes
Did it ever work correctly, or is this the first time you've tried trailering with this CX5? Oh, never mind - I just re-read your original post. Yes, take it to the dealer. Something is very wrong.
 
:
CX-5 AWD, 2017
My cx5 2017 has a dealer installed tow and during reversing with trailer it shuts off backup sensor and even possibly reverse cross traffic brake. I have experienced absolutely no problem while reversing. I think your dealer has used the wrong harness.
 
Top