retrofitting CT5 display in CT4

[Morrob95]

I've tried it a few more times with various attempts at getting the signal to register and no success yet. It's still tiling the output signal but the digitizer is working and registering touches at the correct spots. The boards are different sizes too and I couldn't flex the ribbon cables enough to get the larger screen with the ct4 board without tearing them. I didn't get a chance this week to pester anyone at work for advice but may try next week. Worst case if I decide to abandon it, I have a ct4 and ct5 complete trim assembly that will be getting the carbon fiber treatment.

Hey man;

I just joined this forum JUST for this thread. I recently picked up a CT4-V and the screen is the biggest let-down of the car. If you make any headway, please let me know! I'm looking to do this exact thing. Is it possible to extend the ribbon cable and swap the boards? Or perhaps mock it up in such a way as to test it prior to extending the cable and making it a permanent thing?

 

[jonnywaffles11]

Hey man;

I just joined this forum JUST for this thread. I recently picked up a CT4-V and the screen is the biggest let-down of the car. If you make any headway, please let me know! I'm looking to do this exact thing. Is it possible to extend the ribbon cable and swap the boards? Or perhaps mock it up in such a way as to test it prior to extending the cable and making it a permanent thing?

I was going to comment on this thread soon that I havent tried any other tests of this but have not had any luck when talking to some of the electrical engineers at work about it. Sorry for the let down. I'm currently doing carbon overlays on the trim bezels and once those are wrapped up I'll have an excuse to pull the screen again and maybe will try one or 2 last attempts to wire it up and get some sort of hope. I too am quite frustrated by it and don't want to accept defeat but it's not looking too promising from my opinion.

 

[Morrob95]

I was going to comment on this thread soon that I havent tried any other tests of this but have not had any luck when talking to some of the electrical engineers at work about it. Sorry for the let down. I'm currently doing carbon overlays on the trim bezels and once those are wrapped up I'll have an excuse to pull the screen again and maybe will try one or 2 last attempts to wire it up and get some sort of hope. I too am quite frustrated by it and don't want to accept defeat but it's not looking too promising from my opinion.

Ah man, that blows! I swapped over from a 3 series which also had a disappointing screen. However, I was able to swap to a 10inch android head unit in the 3 series which was really nice. Hopefully something similar comes out. These CT4's don't seem to have a big aftermarket following yet! You have me tempted to grab a CT5 screen and tinker with it though.

One thing I was thinking is does the ribbon cable terminate and is it able to be fully removed? You may get away with not soldering by purchasing another longer ribbon cable! That being said, even if you get it to display properly it seems like you'd need to trim some to be able to mount those two rubber trim pieces so that it all looks stock. Maybe we'll get a refresh in 2024 or 2025 and can simply order that screen!

 

[jonnywaffles11]

Ah man, that blows! I swapped over from a 3 series which also had a disappointing screen. However, I was able to swap to a 10inch android head unit in the 3 series which was really nice. Hopefully something similar comes out. These CT4's don't seem to have a big aftermarket following yet! You have me tempted to grab a CT5 screen and tinker with it though.

One thing I was thinking is does the ribbon cable terminate and is it able to be fully removed? You may get away with not soldering by purchasing another longer ribbon cable! That being said, even if you get it to display properly it seems like you'd need to trim some to be able to mount those two rubber trim pieces so that it all looks stock. Maybe we'll get a refresh in 2024 or 2025 and can simply order that screen!

Yes the ribbon cable can be fully removed and has a lever clamp connector on each end. I have torn more of these cables than I care to admit and am always weary of trying to flex them too much. I'll keep trying to work around some solution and make friends with more electrical engineers at work.

 

[Seth]

Have you tried turning it off and turning it back on again?

 

[Mircrowaved_Bananas]

I've tried it a few more times with various attempts at getting the signal to register and no success yet. It's still tiling the output signal but the digitizer is working and registering touches at the correct spots. The boards are different sizes too and I couldn't flex the ribbon cables enough to get the larger screen with the ct4 board without tearing them. I didn't get a chance this week to pester anyone at work for advice but may try next week. Worst case if I decide to abandon it, I have a ct4 and ct5 complete trim assembly that will be getting the carbon fiber treatment.

I'm an EE I'll try to help out!

Looks like both boards are using an Atmel mXT641T (the microcontroller above the larger ribbon cable header) which, after looking at the datasheet for the part, appears to be the controller for the touch inputs. That probably explains why the touch inputs are working, I bet this microcontroller is running the same firmware on both boards.

Sucks that the ribbon cable lengths and positions don't allow you to use the CT4 board with the CT5 display cause I feel like that could work. I'm curious, what do the other sides of the boards look like? Any components or connectors?

 

[jonnywaffles11]

I'm an EE I'll try to help out!

Looks like both boards are using an Atmel mXT641T (the microcontroller above the larger ribbon cable header) which, after looking at the datasheet for the part, appears to be the controller for the touch inputs. That probably explains why the touch inputs are working, I bet this microcontroller is running the same firmware on both boards.

Sucks that the ribbon cable lengths and positions don't allow you to use the CT4 board with the CT5 display cause I feel like that could work. I'm curious, what do the other sides of the boards look like? Any components or connectors?

I'll get some photos of them side by side tonight

 

[jonnywaffles11]

I'm an EE I'll try to help out!

Looks like both boards are using an Atmel mXT641T (the microcontroller above the larger ribbon cable header) which, after looking at the datasheet for the part, appears to be the controller for the touch inputs. That probably explains why the touch inputs are working, I bet this microcontroller is running the same firmware on both boards.

Sucks that the ribbon cable lengths and positions don't allow you to use the CT4 board with the CT5 display cause I feel like that could work. I'm curious, what do the other sides of the boards look like? Any components or connectors?

@Mircrowaved_Bananas Fix it.....
Ct5 here

 

[jonnywaffles11]

@Mircrowaved_Bananas Fix it.....
Ct5 here

Ct4 here.

Without the backing on the displays I was able to get the main board from the ct4 tied to the connectors on the 5. This is not a viable long term solution though as the ribbons will snap of I try and put it together.

 

[jonnywaffles11]

Other notes of importance. The ct5 DID shop with the 8" display on base models up until ~2020 (original eBay screen was the 8inch and I didn't catch it when ordering). This means there should be a way to do this easily. I never went through parts diagrams to see if any other components had different p/ns meaning like whatever the connectors mount to in the dash if anything there has different computers to output different signals. The fact that the boards are physically so different makes me hesitant to believe that simply swapping the smaller board will make it work. I won't be pulling the screen from my car until I wrap up the carbon trim pieces this week or next but have the donor screens out and can get any info you need from them

 

[Mircrowaved_Bananas]

Ok so spent some time looking at the pictures of the boards. Thanks for posting those. Unfortunately I don't think using the CT4 board on the CT5 screen will work, even if you could physically get them to fit together. The pins used on the connector for the display are completely different between the two boards. It also looks like the CT5 board has an extra controller related to the display.

The two boards are so similar, electronically, in every other regard despite the physical differences. They use the same CAN transceiver, the power conditioning circuitry looks similar, even looks like they are both using the same main display controller, the Infineon S6J342AFTB. It may have Spansion printed on the chip but Cypress bought Spansion a while ago and then Infineon bought Cypress a couple years ago... That was a fun detour trying to figure out what part it was. So in my opinion, not much more you can do in regards to messing with swapping out hardware.

That's a good bit of info that the 8" was used on the CT5 for the first couple years, and then they transitioned to the larger display. Definitely makes you believe that there should be a way to get the thing to work. My guess is figuring out how to change coding, either on the car or the display module, would be the next step. Sadly I won't be of much help when it comes to that as I have basically no experience when it comes to messing with coding GM products.

 

[jonnywaffles11]

Ok so spent some time looking at the pictures of the boards. Thanks for posting those. Unfortunately I don't think using the CT4 board on the CT5 screen will work, even if you could physically get them to fit together. The pins used on the connector for the display are completely different between the two boards. It also looks like the CT5 board has an extra controller related to the display.

The two boards are so similar, electronically, in every other regard despite the physical differences. They use the same CAN transceiver, the power conditioning circuitry looks similar, even looks like they are both using the same main display controller, the Infineon S6J342AFTB. It may have Spansion printed on the chip but Cypress bought Spansion a while ago and then Infineon bought Cypress a couple years ago... That was a fun detour trying to figure out what part it was. So in my opinion, not much more you can do in regards to messing with swapping out hardware.

That's a good bit of info that the 8" was used on the CT5 for the first couple years, and then they transitioned to the larger display. Definitely makes you believe that there should be a way to get the thing to work. My guess is figuring out how to change coding, either on the car or the display module, would be the next step. Sadly I won't be of much help when it comes to that as I have basically no experience when it comes to messing with coding GM products.

thanks for the deep dive. my fear is if it is firmware/coding locked we are SOL. global B is heralded for its encryption, I doubt me asking for root access nicely is going to open it up. I'm trying to think what could be done to force a hard reset and force the system to do a hard boot where it would search for hardware and potentially just register the display and adapt

 

[Mircrowaved_Bananas]

Ah man, that sucks. Not a bad idea to try and get the car to adapt on its own. Did you pull the battery when swapping displays the first time?

 

[jonnywaffles11]

Ah man, that sucks. Not a bad idea to try and get the car to adapt on its own. Did you pull the battery when swapping displays the first time?

I did not but will try that this wekend. Didn't want the battery to trigger anything with OnStar or other crap

 

[Morrob95]

I did not but will try that this wekend. Didn't want the battery to trigger anything with OnStar or other crap

Hey Jonnywaffles11;

Any luck?

 

[jonnywaffles11]

Hey Jonnywaffles11;

Any luck?

nope, had some delays on the trim panels I was working on - ran out of resin - and got delayed a day and a half. I won't have time to try until next weekend now. sorry

 

[Seth]

The day this works is gonna be the best day ever

 

[V_G_M_3pedalonly]

have a ct5, but following this intently bc of how dedicated and talented you boys are... keep up the good work, hope you find a solution

 

[Neveready]

The 2024 ct5 will most likely have this...
There is a fine line between too big and too small. I was in the thousand oaks CA dealer getting the headlight update and sat in both of these. I will admit the 4 screen is noticably too small.

I'm assuming the 5 screen and board won't connect to the HU in the 4. What if you went further down the line to replace the 4 HU with a 5HU?

Some of the extra connections on the 5 may be option specific like vented, heated seats or parking sensors. You almost need a 5 to pull apart or you could back trace it through parts diagrams or service manuals.

I don't know how I feel about the blue, but I know they should have kept Shadow on the roster.

 

[V_G_M_3pedalonly]

I thought they said the 5 wasnt going to get the wrap around... it looks gaudy in anycase, im more than content w my setup, ur supposed to be driving and pushing the car to its limits, who gvs a crap about all the screens, how does that add to the actual driving of the car... meh... if you need that get a merc, frgn car is basically one big screen now
Love the color of that 4 tho... looks sharp