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2020 GLA250 4MATIC Avantgarde Edition
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221 Posts
Discussion Starter · #1 ·
I had aftermarket parking sensors installed in my GLA by the dealer because I was a new driver at the time and I knew that repairs To the car would be expensive. They have been quite helpful despite causing some trouble along the way, and I can now tell you all how to install aftermarket sensors (front+rear) for your GLA after fixing the issues myself.

firstly, you need to find a kit that works for your car. Get a quality product as it will be necessary to remove the bumpers to install or replace them, so you want to minimize the possibility of this issue. The installer put EchoMaster brand sensors on my car, which are good for the most part, but the front sensors rely on CANBUS data from the OBD, which causes a code and prevents the Mercedes Me Connect services from functioning as the car thinks its in diagnostics. I recommend getting a different system like the ones listed below.
MidCity Engineering makes a kit that is specific for Mercedes-Benz, or if you’re in Europe, a company called Braybrooks in the UK makes some too. I’d recommend these, or the flush mount sensor kit from Rydeen is very similar to OEM as well. The most OEM solution is available from David Gold at rollingtones.info. they are made by the same supplier to mercedes and operate exactly as the factory system, minus the auto park function. These are my recommendation as they are best, but if cost is too high or you want something else, the other options are your best bet.

Front
Test sensors before starting the installation because this is A permanent modification.
1. as mentioned above, remove the front bumper to install the sensors. There are a few videos on YouTube for this.
Problems with my GLA45 AMG Panamericana Grill Install
2. Find the markings for the factory sensors near the fog lights on non-AMG/AMG package models or the imitation sensors on the AMG line models. You can place your outer sensors in these locations, or on the AMGs you can remove the little piece of plastic for the false sensors and place your aftermarket sensor body in that hole to prevent drilling anything and to increase OEM stealthiness.

3. The centre sensors should ideally be put in the lower grille to prevent interference with Collision Radar. The installer for my car put them in the bumper right by the radar sensors, which hasn’t cause issues as long as the parking sensors are off while driving, but is not recommended. This is why a quality, automatically activated system is crucial To prevent interferences and to function as an OEM product.

4. mark out and drill the holes. Be careful in this step to prevent mistakes or cracking the bumper. DO NOT drill with the bumper on the car as you can easily damage wiring or other components that are in close proximity behind the bumper.

5. insert sensors and run wiring into the cabin. protect the wires with plastic Loom or fabric tape at least. Enter the car through the passenger side grommet. There are posts on this in other sections of the forum.

6. Power your sensors using switched 12V and connect the necessary signal wires for CANBUS as per your kit‘s instructions. DO NOT use the OBD as it causes errors to occur. Go to a CAN block in the car or follow the kit instructions. 12V can be found using a fuse tap, but if you choose to splice, I’d recommend against using the 12V cigarette lighter/aux plug as this is a permanent installation and having multiple devices powered from this plug can cause the fuse to burn. I believe it's a 10-15 amp fuse and many sensors run at 5-7 amps, so you’ll be using a significant amount of your capacity for it. To keep it simple, locate the small black wire with a green stripe in the bundle of wires leading to the fuse box and use that for switched. this is what my installer did. Alternatively, the red wire behind the radio is 12V switched and can be used as a relay trigger or power source. I would recommend a fuse tap though to prevent issues down the road or to easily remove the power supply.

6. Mount the module and plug in the sensors. My module was mounted under the center console, under the heater controls. you can easily access this area by taking the centre console apart In 5 minutes or less.

7. Reassemble the car after testing the system. Add the user manual to your owner‘s manual collection for your reference and the next owner, or for the dealer to correctly reinstall following servicing/bumper replacement after an accident.

Rear
the rear system is a more complicated installation as you need to access reverse light power or signal to trigger a relay. You have 2 options; disassemble the rear hatch and find the reverse light wire, or 2, remove the radio and find the reverse trigger for the head unit to activate the rear view camera. both options are fairly complicated, but the radio option will take longer as you need to run a wire all the way to the front of the car, but reduces the risk of breaking something as the rear hatch is a pain to disassemble. I will reference the rear option as that‘s probably what most people will do and it is what i have seen done.
2017 Mercedes Benz GLA250 Trunk Panel Removal and Installation
How to fit a Reverse Camera on a Mercedes-Benz A Class W176 2012- 2018

1. if you have LED reverse lights, you will need a CANBUS H7 to eliminate errors. If you don‘t have LEDs, you should be ok, or you can use a relay to power your sensors. I’ll link a video below for reverse light power (non-LED). I have LEDs, so I have the CANBUS. Never had an issue with it, so I’d recommend this.
Wire Backup Camera to Reverse Light CORRECTLY on ANY car

2. you‘ll need to remove the bumper to install the sensors. Reference video. find the markings For factory sensors on the rear bumper. GLA has no dummy sensors, so drilling is necessary for every model. There is a grommet to run the wires into the boot of the car, and I’d suggest looming these wires too.
Mercedes GLA : How to remove rear bumper

3. once you are inside the boot, located A place for your module. there is an access panel on the side of the trunk with a little handle to twist and open. You can keep the module and wiring in there.

4. To run The power wire to the reverse light, you need to remove the weather stripping, pop the clips off of the plastic side panel, run it up to the headliner, through the rubber tubing that has wires to the inside of the hatch. No easier way. Make sure to tuck the wire deep inside the gap where the weather stripping goes to ensure the seal goes back completely as water intrusion will damage a lot of the expensive electronics in the car and won’t be warrantied.
2017 Mercedes Benz GLA250 Rear Fog Light and Reverse Light Replacement
2017 Mercedes Benz GLA250 Brake Light Replacement and Tail Light Installation

5. now, start the car and put it in reverse. Ensure the system works and no errors occur for the reverse lights. If there is an error, check your connections and make sure you’ve wired everything correctly. If for some reason The CANBUS doesn’t work on your car, you can use a relay system to get signal from the reverse lights and power from the rear 12V socket. You can use the rear 12v because usually it is only in use when the car is parked and you’re only drawing current from there when the car is in reverse. This should not be your primary power source though, try to use the CANBUS because its the simplest and cleanest method.

7. Reassemble the car and observe sensor function over the next few days to ensure no errors or interference occurs. If your sensors are interfering with other vehicle functions, you may need a different kit. The ones I’ve suggested are most likely to Work best and are designed for mercedes, with the exception Of the Rydeen.
 

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How do the proximity indicators work? On the OE system you have two bars.. one in front on the dash and one in the rear at the top of hatch to tell you how close you are to hitting something, plus a graphic on the backup camera. Anything like that with this or do the sensors just yell at you?
 

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2020 GLA250 4MATIC Avantgarde Edition
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221 Posts
Discussion Starter · #4 ·
How do the proximity indicators work? On the OE system you have two bars.. one in front on the dash and one in the rear at the top of hatch to tell you how close you are to hitting something, plus a graphic on the backup camera. Anything like that with this or do the sensors just yell at you?
Yes, I have fitted two displays, both in original locations. I didn't attach photos because there was a limit to how many I could add. Depending on what system you buy, there may or may not be displays. all of my recommendations do have them and they all look like OE displays.
there is no graphic on the backup camera because this is a universal aftermarket system, but Rydeen has an interface that allows a distance display to appear on your screen. not sure if it works for Mercedes but I know for sure it doesn't look like the OE diagram.
 
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