Ok, I'm doing a little fact checking before I jump into what could be an awesome or catastrophic project. I'll try to keep the word count down but it's a little complicated so bear with me.

Background: I've been looking into car computers, in the form of a single board computer (Google raspberri pi car computer for baseline info) and a touch screen lcd. Essentially it's a d.i.y version of what most modern cars have in the center dash area except it would be a fully functional computer and all that that entails. It would connect to the OBDII port for diagnostics, would have WiFi, radio, Web browser, the works.

Well, I found and even cooler idea. An LCD gauge cluster. Like some modern cars. It would boot up with an automotive dash program (there are a bunch on the Web with various levels of sophistication and visual appeal) and function however you want it to.

Now: getting such a system to work is easy. It's just a tiny computer with U.S.B ports and various aftermarket hardware boards for whatever you could want. But at its base, it's a tiny computer, an LCD screen, and a chord or Bluetooth connection to the OBDII port. The computer and software gets everything it needs to operate from the OBDII port and off you go.

Questions I need answered: ok so the factory gauge cluster would be gone, obviously. I know that the factory cluster talks to the BCU.

1: So, will the vehicle operate without the cluster? Is there a chip in the cluster that the bcu needs to recognize?

2: the dummy lights such as blinker indicators and MIL, are they controlled via an interface through the cluster, or can I simply tap into the pertinent wires coming from the BCU?

3: these OBDII programs that people are using are utilizing universal language to talk to the engine computer, but as with hand held diagnostic tools, the ABS and BCU computers require some different kind of language to access. Is anyone familiar with land rover computers enough to give me any info on possibly talking to these computers, even if it's just on a programming level?

 

Sounds like the D2 Electrical Library might be useful to you in terms of understanding what signals are sent to/from the gauge cluster. I found it as a single PDF using a web search.

 

Ah, completely forgot about that. I'll try to find it, thanks.

Don't let that deter yal from further input lol, I'm no electronic genius and I'm definitely sailing on stranger tides with this one.

 

You're a saddo KingKoopa, nothing better to do eh .

Be careful as the BCU recognises the gauge cluster for the mileage etc and it may disrupt it's mind if you change it. Try the electrical library as Mollusc says before you tear down the cluster.

 

Lol, I can ever convince myself to buy a new vehicle, but I walkways want my old vehicles to have the coolest tech.

Yeah I've actually got a 2003 ecu, bcu, and gauge cluster in my 2004. To avoid paying a mechanic to sync all of them together. That's part of my issue is that the bcu contains the odometer reading. If I can't read the bcu and display it's data, then I don't have a fully functioning dash. I maybe be able to remove the small odo screen from the original cluster and integrate it into my digital one.

 

The odometer data and cluster registration won't be contained within the display -- there will be some kind of chip that holds those.
I wonder if it would be possible to retain the circuitry of the original cluster -- hidden somewhere back under the dashboard -- and install the new visualisation system as well? The new components would simply take whatever signals are needed from the cluster circuitry and the OBD port but since the old circuits would still be there, you wouldn't run into problems with the odometer or other gauges and lights.

 

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Indeed that's what I'm thinking it's going to take to make it work. I had hoped on using a screen that was the same size as the opening In the binnacle, but I might have to make room on the sides for dummy lights and possibly the ODO screen from th factory cluster.


Perhaps I can isolate the chip and it's board and remove it from the rest of the printed circuit board, so I only have one small component to tuck back up in the dash.


Personally I don't care anything about seeing the total milage, the short term ODO would be GPS controlled. So the only issue Is making sure that the vehicle operates, and that I am notified when there is an issue that is related to any of the computers on boards.

 

Its not just the BCU, SLABS has its own serial data line to the gauge cluster
The coolant and tach both have their own PWM signal from ECU to GC
brake,temp, SRS,Check Engine warning lights are 12v logic. Fuel gauge is analog input.

RAVE describes enough of the wave forms and voltage levels that it'll give you a good start reverse engineering them. You could skip a few like tach and coolant temp and use the iso9141 data from the obd2 port instead, but the updates will be slower that way and those are the lowest hanging fruit in the reverse engineering portion of this project.

Seems like a ton of work for something that if it ever does look right will be incredibly dated in about 5 years, and doesn't offer anything you don't already have other than the possibility of a linear temp gauge. Maybe try driving around with an Ipad over the dash running an obd2 app, because thats essentially what you are doing.

 

Good info, thanks man. I have an extra GC in the garage, I think Im gonna take it apart and see how involved the printed circuitry is.

As far is it being dated, the idea of a digital dash might fade out of the limelight but the styling can be changed at will, because it's digital lol. In theory I could replicate the look of the factory GC. I just love the idea of being able to see GPS at will right in front of me, flip a switch to real time diagnostics, and all the while have standard gauges waiting on another screen or superimposed the whole time.

Can you confirm or deny that in a worst case scenario, the vehicle will operate with no GC plugged in? This stems from curiosity more than anything at this point because it sounds like ill need to integrate the stock GC to some extent anyway.

Edit: not to mention, part of the appeal is that it's cheap. Hardware for something like this should be less than $200, possibly under $100 depending on the screen and OBD interface I use.

 

I don't know if it will, but I don't see why it won't. I've only messed with intercepting the ecu to gc temp signal to build a linearized temp gauge driver.

From my understanding the only problem with the odometer membory check is if the mileage is lower than the bcu it corrects itself, but if the otherway around it throws an asterick next to the display. I may be confusing that with what BMW does, so don't take that as gospel.

It sounds like you want linux based small board computer. I don't know of any that have a native ADC you'll need for the fuel sending unit so you're going to have to stack a bunch of other stuff or build something custom. If you go custom board the l9637d is an easy way to interface the obd2 port and update speeds will be as fast as possible, unlike a plug in obd2 to serial adapter.

Watch the temp ratings. A cheap hobbyist lcd screen will not last in a car interior during the summer. An ipad can't even do that.