GR Yaris Facelift Yaris Headunit Retrofit - Is it possible?
- Thread starter GR17
- Start date
GRavy_Baby
Obsessed member
It fits physically, just as expected. The wiring, though... not even close.
The sensible thing would be to return it and call it a no-fit.
But I'm kind of hooked on it now. Damn it!
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tonic
Totally Hooked
- Aug 31, 2023
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ThanksLOL you went LARGER!?
Most people doing these wanted it less encroaching on the windscreen lol!
Looking at it, I guess it's just going to block your vents a little...
Good luck!
My seat is lowered by 30mm, and I've never had issues with the head unit obstructing the windshield.
The new head unit sits about 4mm higher, but there's still ~15mm gap to the bottom edge of the windshield.
tonic
Totally Hooked
- Aug 31, 2023
- 207
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Here's an update.
After spending way too much time digging through Toyota Tech manuals, Amayama catalogues, and Ovoko listings, I think I'm finally on the home stretch of piecing together the 10.5" head unit puzzle.
The issue is that this head unit is much more common in the Yaris Cross than the regular Yaris. As a result, used Yaris Cross parts are easy to find, while Yaris parts are pretty rare. Some components are identical but have different part numbers, while others are completely different because the lower dashboard design isn't the same. Buying everything new from Toyota would be the easy option, but it would push the cost well beyond what makes sense for this project.
Here's what's needed to fit the 10.5" unit into a Gen1 GRY.
Parts shared between Yaris and Yaris Cross:
The options are:
The GPS, FM, and DAB antenna connectors are different too, so it looks like part of the antenna loom and the GPS module under the dash will need to be swapped. The original antenna wiring uses larger connectors, so they're not directly compatible.
The USB connector is another difference. It can be cut and wired to the GRY one, but the 10.5" unit uses USB-C and I want a proper USB-C PD charging. The USB-C modules from the Yaris and Yaris Cross have a different shape and won't fit the GRY.
However, it looks like the Corolla Cross uses one that should fit the GRY location. I've got one on the way, so I'll know soon enough.
That's where things stand for now. I'll post another update once the remaining parts arrive and I can start putting everything together.
After spending way too much time digging through Toyota Tech manuals, Amayama catalogues, and Ovoko listings, I think I'm finally on the home stretch of piecing together the 10.5" head unit puzzle.
The issue is that this head unit is much more common in the Yaris Cross than the regular Yaris. As a result, used Yaris Cross parts are easy to find, while Yaris parts are pretty rare. Some components are identical but have different part numbers, while others are completely different because the lower dashboard design isn't the same. Buying everything new from Toyota would be the easy option, but it would push the cost well beyond what makes sense for this project.
Here's what's needed to fit the 10.5" unit into a Gen1 GRY.
Parts shared between Yaris and Yaris Cross:
- 10.5" head unit – 86140-0D721. There are different versions for various markets and the premium 8-speaker system, but this one appears to match the GRY CP audio setup.
- Head unit trim – 55420-0D041. There are a few variations, but most should fit.
- Air vents – 55670-0D660 (also listed as 0C5652D650, 0C5641D650, 0C5642D650).
- Center air duct – 55086-0D050.
- Lower dashboard trim – 55435-0D290(-C0). This has the wider opening for the larger vents.
- Locating bracket (replaces the storage tray under the vents) – 55445-0D220. I had to order this from Toyota since the Yaris Cross version doesn't fit. Still waiting for it.
The options are:
- Replace the whole dashboard panel (expensive and a lot of work).
- Trim the interfering section (works, but there's no going back as the original tray loses its main mounting points).
- Design and 3D print a custom air duct that connects the original GRY duct to the new center vents. That's the option I'm leaning towards.
The GPS, FM, and DAB antenna connectors are different too, so it looks like part of the antenna loom and the GPS module under the dash will need to be swapped. The original antenna wiring uses larger connectors, so they're not directly compatible.
The USB connector is another difference. It can be cut and wired to the GRY one, but the 10.5" unit uses USB-C and I want a proper USB-C PD charging. The USB-C modules from the Yaris and Yaris Cross have a different shape and won't fit the GRY.
However, it looks like the Corolla Cross uses one that should fit the GRY location. I've got one on the way, so I'll know soon enough.
That's where things stand for now. I'll post another update once the remaining parts arrive and I can start putting everything together.
Last edited:
tonic
Totally Hooked
- Aug 31, 2023
- 207
- 658
I'd like to keep the original tray, but there's really no way to do that with the new vents since they take up the entire space where the tray sits. The part I'm working on is an adapter that connects the new vents to the black plastic duct coming from the HVAC unit. I've already modeled the connecting parts (red and light blue) for the new vents and the original duct. Now I need to connect those together into a single part.
tonic
Totally Hooked
- Aug 31, 2023
- 207
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Steering wheel buttons, microphone, USB-C, and the reverse camera all work as expected.
The FM radio and navigation still need a new antenna harness, and possibly a different GNSS module under the dash.
The reverse camera image doesn't look great on the larger screen, so I'll probably replace it with a newer camera at some point.
The head unit is still registered to the previous owner, and I haven't been able to remove it. I also can't add my own because the unit runs into some kind of error. My guess is that the original GR Yaris telematics module is different and doesn't support whatever network connectivity this head unit expects. Connecting to the WiFi does not help.
Android Auto works fine over USB, but I can't enable wireless Android Auto even though the head unit definitely supports it. That could also be related to the account issue or the fact that I'm stuck in guest mode.
Overall, I'm really happy with how everything turned out. There's still a bit left to sort out, but it's definitely getting there.
tonic
Totally Hooked
- Aug 31, 2023
- 207
- 658
Thanks mate. I've actually got the wiring sorted already - it's pretty much identical to the table posted above with just a couple of minor tweaks.
Right now, the main goal is figuring out the antenna and data connection over the DCM.
Well done! 
tonic
Totally Hooked
- Aug 31, 2023
- 207
- 658
A few more updates on the swap.
It turns out wireless CarPlay actually works. I'm on Android, so I hadn't tested it before. Wireless Android Auto, however, needs the GPS antenna connected so the unit can decide on 5GHz Wi-Fi use depending on the area it's in.
So, all good then. Not really.
A few days later, the car battery was dead. I recharged it and measured the current draw — 0.7A with the car locked, and it wouldn't drop any further.
Normally it sits around 0.02–0.04A when all the ECUs goes to sleep.
I checked the head unit itself and its current draw when turned off was negligible.
I then depinned the CAN bus wires, and the current draw settled at around 0.03A.
That sent me down the rabbit hole trying to figure out why.
It looks like the Gen1 GR Yaris ECUs register themselves on the network when the ignition is turned on. Later, when they receive the sleep command, they acknowledge it and the CAN bus goes quiet.
The 10.5" head unit seems to have a different approach to network management. It doesn't really care about the rest of the GRY network and keeps talking its own dialect, preventing the CAN bus from going to sleep and consequently keeping the other ECUs awake.
There are a couple of ways this could be solved. One would be a custom head unit gateway that behaves like the OEM unit and filters out the chatty 10.5" radio. The other would be simply disconnecting the CAN wires with a DPDT relay when the ignition is off.
Neither is particularly "OEM elegant", they're basically workarounds.
While digging through the CAN traffic from the 10.5" HU, I also found around a dozen new CAN IDs that aren't present on the Gen1 network. I assume they're harmless apart from adding some extra traffic to the bus.
At this point I'm not sure whether I'll stick with this head unit. The display itself is really nice, but I'm not a big fan of the workarounds and compromises needed to make it play nicely with the GRY.
It turns out wireless CarPlay actually works. I'm on Android, so I hadn't tested it before. Wireless Android Auto, however, needs the GPS antenna connected so the unit can decide on 5GHz Wi-Fi use depending on the area it's in.
So, all good then. Not really.
A few days later, the car battery was dead. I recharged it and measured the current draw — 0.7A with the car locked, and it wouldn't drop any further.
Normally it sits around 0.02–0.04A when all the ECUs goes to sleep.
I checked the head unit itself and its current draw when turned off was negligible.
I then depinned the CAN bus wires, and the current draw settled at around 0.03A.
That sent me down the rabbit hole trying to figure out why.
It looks like the Gen1 GR Yaris ECUs register themselves on the network when the ignition is turned on. Later, when they receive the sleep command, they acknowledge it and the CAN bus goes quiet.
The 10.5" head unit seems to have a different approach to network management. It doesn't really care about the rest of the GRY network and keeps talking its own dialect, preventing the CAN bus from going to sleep and consequently keeping the other ECUs awake.
There are a couple of ways this could be solved. One would be a custom head unit gateway that behaves like the OEM unit and filters out the chatty 10.5" radio. The other would be simply disconnecting the CAN wires with a DPDT relay when the ignition is off.
Neither is particularly "OEM elegant", they're basically workarounds.
While digging through the CAN traffic from the 10.5" HU, I also found around a dozen new CAN IDs that aren't present on the Gen1 network. I assume they're harmless apart from adding some extra traffic to the bus.
At this point I'm not sure whether I'll stick with this head unit. The display itself is really nice, but I'm not a big fan of the workarounds and compromises needed to make it play nicely with the GRY.
