Seat Ibiza rear parking sensor retrofit

[Sketch]

First of all, if you're thinking about saving money by not speccing parking sensors from factory - don't! You won't save any money, in fact you'll probably spend more, not even including the time and headaches it'll take. E.g. for my car it was £200 from factory - however I bought it used without them. I would've spent a bit to a lot more + having to get a tool like obdeleven/VCDS.


Otherwise if you want/have to install it yourself, if you can, buy a whole installation kit. Make sure it comes with a control unit etc, so it integrates with the media unit ("optical" parking sensors). You can pick up buzzer only sets, that are a lot easier to install and are simply wired into the reversing light's power, but keep in mind they are unlike the OEM installation.


Seat dealers offer a "Seat verified" aftermarket installation, but since they cannot get the parts, which we can get from e.g. salvaged cars, they install a "dumb" pdc system, so only with a buzzer - which would've run me £350. This forums sponsor offers a proper kit - installed for ~£700.


My car is a 2020 Seat Ibiza Tsi Fr 115.

So first of all, you'll need parts.
A good source, I found for "OEM-esk" parts is KufaTec. They're a bit expensive, but have good support and decent cables. They do also offer a full installation set for ~£300-350, iirc. They also provide installation manuals, but they are generic, for older cars, I suppose they sort of give a rough guidance. I saw a kit for £250 and in all honesty I would've preferred buying that over buying the parts myself. I can't remember where I saw it unfortunately.
My other sources of parts were Ebay, oemvwshop.com (- expensive shipping and some used/copycat parts -) and AliExpress for some random connectors, etc. where you can't really do anything wrong.




Parts needed:
• Wiring loom car ("main wiring loom") -> pdc -> parking sensor connector & buzzer (KufaTec - ~£54)
• Rubber grommet (Came with the above loom - S/N??)
• Buzzer (5Q0919279 AliExpress - they're usually fine - £2)
• Control unit (5QA919283 - B/D/H/G, Ebay - £15-25 - Coded to 3 sensors)
• Parking sensor wiring loom (off Ebay, from the previous generation car - £72)
• 3 parking sensors (5Q0919275B - got them with the above loom)
• 3 parking sensor rubber seals (5Q0919133 9B9 - oemvwshop - £0.18 each - also were already on the above sensors)
• 3 *different* Sensor holders (6F0919486, 6F0919486A, 6F0919486B - oemvwshop - ~£10 per)
• Hole cutting tool (BEA000001 - oemvwshop - £5)
• Some insulated wire (preferably the color of the Can bus wires you're connecting to, so brown/orange & black for me)
• 7.5A fuse
• Connector parking sensor loom -> main loom (AliExpress - £2.5 - ALWAYS order male & female, as they might manage to copy the pin layout from Seat, but not the correct size of the connector - I needed this because the previous gen parking sensor loom has a different connector)


Tools:
• A trim removal tool set can be useful and I got some 234 (- a lot of connectors really -) tool set for £10 off Ebay; did the job, can't complain about the price.
• Soldering iron
• Pliers, wire cutters and - strippers, needle-nosed pliers
• Some thin, moderately stiff metal, e.g. feeler gauges, to hold a bunch of cables apart and isolate the others behind the one you're working on.
• Various other tools
• Duct & insulating tape
• Star Alan keys
• Alan keys
• Spanner (for holding the hole punch - not really necessary, in fact, they might even be in the way)
• Hand cleaning wipes
• (CA) superglue



Steps:
1. Connect the main wiring loom to the car
2. Temporarily connect the control unit, buzzer and sensors and code to check if all works
3. Disconnect sensors, route the cable through the car into the boot
4. Place rubber grommet, push parking sensor wiring through, fit connector and connect to main loom
5. Drill pilot holes in the bumper, use the punch for proper holes
6. Fix parking sensors using the holders
7. Close back up - done
Simple, ... right?



0. Disconnect the battery! *Before* you connect to anything on the car!!!


1. Main wiring loom

Off this should come various cables. A connector with 5 wires for the parking sensors, a connector with 2 wires for the buzzer, a ground, ignition positive, can high & - low and the connector to the control unit.

There are four cables you need to connect:
ground, ignition positive, can h/l.
First, check in the fusebox for a ~12V unused fuse spot that is only live while the ignition is on.
Then, make sure the car battery is disconnected (- removing just one of the connectors will do the job - Minus is usually easiest to remove).
Push the "|\/|"-shaped ignition plus clipping connector into the spot in the back of the fuse box, which you checked before. You can take the fuse box out by releasing some clips (only clips) to do this, but it's not strictly necessary. Then protect it with a 7.5 Amp fuse.

The ground wire simply bolts onto the ground of the car's chassis, or whereever you find a ground. Mine was behind the side trim panel of the dashboard.
Through there you can also see the following connector:

The can bus connector you need can be found on a box (Gateway) like this, perpendicular infront of the fuse box.

For me it was the connector at the top, looking at how it's placed in the car.
It has a white bar that lifts up and then pulls out. It'll need a bit of convincing to make it even a little bit easier to access. Then, take it apart. I know this might sound scary, but you can't really do anything wrong. First, cut the zip tie for easier access, but not any cables.
There are two plastic clips and once you've released them, the two white plastic connector blocks slide out. It's quite obvious where they slide out.
On one of the two blocks there should be four pairs of can cables,
Extended can: blue/orange&brown/orange
No idea: red/orange&brown/orange
Drive train can: brown/orange&black
^^^ WE WANT THIS ^^^
"Convenience" can: green/orange&brown/orange

We want the drive train can, on the brown-orange (can low) and black wires (can high), on pins 44/45.
Make sure you don't solder the control unit's cables directly onto here, but rather connect an intermediate wire, in case my information is - or you get it - wrong.
Place something thin, metal between the cables, so only the wire you are soldering onto is on top of it, strip a tiny bit of it off with e.g. a scalpel - CAREFUL!!! - only cut the insulation of the cable and solder onto it. Then put some insulating tape around where you soldered and your cable. Make sure it won't make contact anywhere. Repeat for the other cable.
It helps if you place some solder onto the end of your cable before you try fixing it into position.
Mine would've looked something like this without the tape on them:

Push the two blocks back into the connector, replace the ziptie, and place it back onto the Gateway box.



The control unit:
You need a control unit with the serial number 5QA919283 - B/D/H/G, which comes from a car with 3 parking sensors. It can be parameterised to accept 3/4 sensors, but you cannot do that with ObdEleven. These units may differ in their pin layouts however.

 

[Sketch]

2. Testing:

Your parking sensor loom should not have a connector on the end of the pins.

If it does, you will need to remove it, as it has to fit through the rubber grommet.

If the wires from the loom are not labelled, you will need to figure out which one each is. On the parking sensors you can look which cable runs to each sensor. Plus the 2 that run to all of them.

Use some heatshrink (not heated up) to place over the 5 pins, and temporarily slot them onto the corresponding connector coming from the main wiring loom.

The corresponding connector should be a 2x4 connector with 5 wires in it. Pin 5 - ground(/minus), Pin 8 - ign. plus - Pins 1,2,4 parking sensor "feedback" (on mine). These may vary, so be sure to measure what they do (e.g. resistance ground to ground & voltage (~12V) ign. plus to ground, while the ignition is on, and the main wiring loom is connected to the control unit).

Place the pins of the parking sensors on the correct pin of the main wiring loom connector (the order of the parking sensors doesn't matter yet).

Since these are rather loose, be careful with them and only swap them with the ignition off.

Connect the parking sensors to the parking sensor loom and the buzzer to the main loom.

Reconnect the battery, plug your obd reader in and turn on the ignition.

Now you will have to code the parking sensors.

• 5F Multimedia >
- Adaption
# Vehicle function list BAP
-> Parking Assist 0X0A: Activated
-> Parking Assist msg bus: Terminal 15
# Vehicle menu operation
-> menu display pdc: Activated
-> menu display pdc over threshold high: Activated

• 19 Gateway
- Security Access: Enter code (20103)
- Adaption
# Installation list
-> Parking Assistance: Coded

• Reload Control Unit list, if it's not there, add 76 Parking Assistance with the button at the right bottom. 76 Parking Assistance should show up in the list. The icon (76) should not be grey. If it is, your main wiring loom is not connected correctly. Try swapping can high/low over.

• 76 Parking Assistance
- Correctly adapt to your car:
- Security code (71679)
- Long Coding: Configure, e.g.:

I was told the following needs to be done on some (possibly older) cars, but it was not needed on mine:

• 01 Engine
- Security Access (27917)
- Long coding
# Byte 3
-> Toggle Bit 5 ON

• 03 Brakes
- Security Access (20103/40168)
- Long Coding
# Byte 47
-> Toggle Bit 3 ON
# Byte 51
-> Toggle Bit 4 ON


Confirm these changes, clear error codes and turn the car off.

Start again, pop into reverse and the sensors should work (and show up on screen - as 4 lines, always 4).

if you still get a "L/C/R parking sensor open ground" fault (and the sensors don't work), read this:

Turn off the ignition.

You need to measure which pins are the right ones. (There should be 4). Take the *disconnected* Control Unit and measure the resistance between each pin and ground. A parking sensor pin should measure around 141kΩ. Now you need to swap the one not working pin(s) onto the (other/)4th possible pin, which is currently not connected. You can easily slide the connector block out of the pdc unit connector, after removing a plastic cover (at least on mine), and get the wire out of the slot with a pin. Then simply slot it into the correct slot and close up.

This is most likely because your connector is for a different car than your control unit is parameterised for. Usually only the parking sensors are wired incorrectly.



3. Installation

I duct taped the control unit into place onto the plastic which holds the fuse box in place. Apparently there are proper clips for the control unit, but I couldn't find them and they probably are only there if you have sensors from factory.

Lift the door sill trim, all the way to the back. For me, what worked best was sadly brute force, no trim removal tools - they are way too weak for the job. Wire the cable from the foot well all the way to the back seat. Remove the panel next to the back seat rest (on that side) and push the cable through into the boot.

Remove the entire trim on both sides of the boot, the bits of fabric lining and plastic trim at the top. You can route the cable along and have it end up at the right front bottom of the boot (looking into it).

Remove the boot sill trim.

There is a rubber grommet on the right which is covered, where we will route the parking sensor loom though. Remove the rubber covering.

First, lay the buzzer cable along the boot sill, to the passenger side. Then place the buzzer somewhere there (e.g. on top of the indent and duct tape it into place. There should be some fixture, but since the sensors are not preinstalled I believe it is missing. Fix the cable into position as well.



4./5. Bumper and sensors

Undo a white plastic bolt with a spring and a wing (like on a wingnut) on it on each side of the boot, which holds the rear lights in place. Next to those will each be a connector for the lights, which need to be disconnected. Then the lights simply pull out (with a bit of force).

Undo bolts on the edge of the wheel arching on each side, there should be 4, that (obviously) go into the bumper.

Pull the bumper off the clips beneath where the lights were, by pushing the clips in. Then pull the top of the bumper away from the car. There should still be clips holding the bottom of the bumper in place. Do not remove these, as they should not impact how easy it is to drill holes and they're a pain to get back in.

You should now see markings for the parking sensors (x marks the spot).

Use a small drill bit to drill towards the outside of the bumper. Then move to the outside and use a drill bit to create the hole for the hole punch (8mm).

Use the hole punch (with the small bit on the outside of the bumper, to pull the plastic inside, towards the car.



6./7. Fix sensors in place, close back up

Now, I am not sure whether the main loom -> parking sensor loom connectors are meant to sit outside of the boot in the bumper or in the boot, but I placed them in the boot. It was a very tight fir however, maybe just because my wiring loom is from the previous gen car. Otherwise you would have to remove the connector from the main loom instead and push those through the rubber grommet.

Pull the wires at the end of the parking sensor loom through the rubber grommet.

The "pin" on the grommet should be facing towards the back of the car and pointing downwards (put the wires through the right way).

Then mount the sensors to the bumper, after wiping any dirt off with some wipes.

Use the correct sensor holders (A right, B center, " " left), push the sensor into each and stick them to the bumper. A little superglue can't hurt. Use the biting clips on the wiring loom to fix the loom to the bumper (there are special ridges) and mount the one clip that sticks to the bumper as well (clean and maybe superglue).

Make sure the rubber seals are properly squeezed into the holes. Maybe either way, take the sensors out of the clips, which are stuck to the bumper, and put them back in. Put a lot of pressure onto them so that the seals sit tight in the bumper.

Then push the bumper close to the car, push the rubber grommet through the designated hole (squeeze it together).

You can pull the bumper onto the ridge of where it sits by the boot sill, but don't clip it in place yet.

The connector should have come with clips that cramp onto the ends of the wires ("|\/|" & opposite "/\"), with a rubber seal around the end of the wire. You should've already fitted these to test the sensors.

Connect the wires temporarily into the main loom connector again, and test which sensor is which. Then push the wires into the correct slots on the parking sensor loom connector and push that into the corresponding connector on the main loom. Push the rubber blanks into the unoccupied slots, as seals.

Push the bumper back into position and put the screws on the wheel arching back in.

I Duct taped the pdc loom connector into place as well, so it wouldn't rattle, and hid it just behind the felt boot trim by the grommet.

Then put the lights back in place, screws and connectors, and of course all of the boot trim.

Congrats, your bumper should look like this now:

And the pdc display like so:

I wouldn't have been able to do this without help from @przebiegly

Thank you so much!



Any questions, I'd be glad to help with.