It was requested I start this thread in an effort to stop the derails in the obsolete tech thread over in PYF. It's main purpose is for the couple of people there interested in asking more to do so here so I don't be a thread whore and annoy everyone.
Preamble: I am a silly silly single-minded fool with just enough brains to not break things and NOT an expert what so ever.
Anyway, the story starts with an impulse purchase of a near new car that was very cheap (this isn't a story of a lemon though, good news!), flew 800km to pick it up and on the long drive back I realised I was a fool for buying such a new car that only had a single CD, AUX in and radio.
This modern age and it's influences means I must MUST carry every drat song I have ever listened to or hoped to listen to with me at all times, especially when driving.
I could have gone and bought a FM transmitter and be done with it, but drat IT! I want to retain steering wheel controls because I am a special snowflake.
So, to the internet to research aftermarket headunits to replace, but as is the way with modern cars, the standard DIN system was not in the interior engineers' mind when designing this car.
A friend of mine had the next series of this car, which came with the flash bang gee whizz touchscreen navigation, USB, CD ripping and BT entertainment system as standard. After a lot of research and screwing around with my DMM I found out the difference in the wiring looms between his car and mine. That was the first step, the easiest.
Next came the task of getting the parts database for this vehicle and seeing the parts commonality of trim and if they are interchangable. After theory crafting a plan, my gracious friend let me tear into his vehicle and start seeing what I can see. I had a weeks access to his car while he was away for work so no time to waste.
With the physical data connection figured, came some GMLAN bus sniffing with an ELM CAN scanner and a Tech2 I had access to. So after figuring out how the BCM talks to the HU, how the HU talks to the front facia and HVAC module, and how the steering wheel controls talk to the HU I was confident all I had to do was reprogram an EEPROM inside the HU and trick the HVAC into thinking it was a dualzone unit (AC controls were part of the facia) with a reflash and resistors soldered on it's PCB to temp sense pins to emulate the additional sensors that the dualzone has.
On the HU side of things, I was positive that the vehicle VIN number would be in there somewhere. I ripped my series 1 unit apart, and low and behold, the last 10 or so characters were reversed in plain text. I tested changing this to my partners series one, plugged it into her car and yep it worked! OK so now to do the same with the series 2 one.
This was a little more tricky. I am going from memory here as this was maybe 2 years ago now but the .hex of the EEPROM of the series 2 unit didn't have the convenience of reverse order.
So I head scratched, checked other boards and chips for anything and returned to the first EEPROM and checked it's dump again. at 3am one night I had a thought and checked closer - yup there it was, right in front of me!...
Think of the last 10 characters of VIN as:
The data reflected this pattern:
Lazy, lazy engineers!
Anyway, so that's pretty much it. No CRC checks, no fuckery, just a pin remap for physical connection, a few new pieces of trim, a reflash of two EEPROMs (one could be done with scantool), a few resistors and bingo! I have a touchscreen MP3 CD player with navigation and its all factory. The last issue was getting USB/iPod integration. A curious 4 pin board connector on the left side of the HU behidn the dash revealed itself to me as a USB interface with the datalines reversed to the normal pinout.
Some random photos:
BEFORE stock photo of the stereo:
(yes in the rush I forgot to install the air vents!)
Humphreys fucked around with this message at 07:38 on Mar 5, 2015
|# ¿ Mar 5, 2015 07:24|
|# ¿ Aug 10, 2020 16:05|
Commodore? VXR8? Looks almost identical to interior trims I had on my G8. If you haven't already chatted with the G8 forum dudes they would likely be very interested in this mod. Some guy over there charges hundreds of dollars to re flash head units to display video in motion and all sorts of other craziness. There's also a mod where the HVAC controls are replaced by an aftermarket touchscreen (that probably sucks) in order to go to new head units due to the HVAC control integration.
Commodore. And yes, no one gives up the simple secret to VIM without $$$ being handed over. I looked at the replacement HVAC screen while it was in development (it was at this time I was doing my mod) and it looked janky as gently caress. Apparently it is much better now, even ways of intetragting it with one of those fancy rear end (sluggish) android Headunits.
I googled around, and yeah the mod seems kinda easy and well documented nowadays...gotta hate that!
The one thing I would not mind is flashing custom startup graphics but that required a different programmer which is expensive (from what I remember).
|# ¿ Mar 5, 2015 10:40|
Unfortunately for me I found that site shortly afterward while googling for a steering wheel removal :/ .
If you did most of the write-ups there, awesome work! I looked at the auto-dipping mirror stuff and thought against it.
A question for you though: In the future I may want to upgrade again to a new after market unit, how well do those HVAC replacement control units go?
Also to prove how much of an idiot I was when I did this. I didn't realize that the bluetooth was a separate module that was hidden just to the left of the HCM the whole time. I had just never turned on BT and never read the manual until afterwards.
|# ¿ Mar 6, 2015 07:23|