Reverse engineering the data going to a Prado inclinometer (1 Viewer)

[pomtom44]

Hi all.

First post so hopefully not breaking any rules.
I recently purchaced a 98 Prado, which came with the stock inclinometer, however the backlight on it was broken.

rather than replace it, I decided to make my own using a araspberry pi and arduino.
I have put some of my own sensors on it, and slowly getting there with the display,
However Id like to see what data I can pull from the engine.

Doing a search online, I have found a few posts of people on here talking about the same display unit, however its always about installing the display, and not the data its self.
The closest I have found in this post

Clinometer/Compass Meter Option

First post in this section.:D Could somebody tell me which year model LC Prado (90?) that these units came out of? Did they all come with the option and if not, is it really a plug-and-play like the CLD switch of the 80 (harness tucked away right behind the console panel)? Thanks in...

forum.ih8mud.com

Where there is a wiring diagram, but no info about how the data is being sent.

Ideally I would like to use the external temp sensor, so I would need to know how that works
I assume some sort of voltage range being converted into degrees, but I dont know what that range is (or where the sensor is so I can check part numbers)

Also trying to figure out what data is being sent via pin 7 (marked as mulitple instraments?) SO I assume some sort of encoded message being decoded on the chip on the display?

Any ideas where I can start with this?
Thanks in advance

 

[Jaymes]

If you can figure this out I would definitely be interested in how you do it. Good Luck. I have tried (semi successfully) to restore the one on my rig, but lost the compass in the process, and must have used the wrong polarizing film on the screen. I would love to keep all the functionality of the unit though.

 

[pomtom44]

If you can figure this out I would definitely be interested in how you do it. Good Luck. I have tried (semi successfully) to restore the one on my rig, but lost the compass in the process, and must have used the wrong polarizing film on the screen. I would love to keep all the functionality of the unit though.

So far I have managed to confirm the pinout from a spanish post I found online.

I have 12+ (both ign and bat) and ground.
Light sensor (So i can control the brightness of my screen when i turn on my headlights)
im pretty sure I know which are the external temprature sensor, although not sure how that works yet
and iv probed what is marked as "instruments" and gotten just over 5v from it,
I dont have an osilosope to check if its a signal or solid 5v, so may need to find someone who does who i can borrow from

 

[John Young]

Well, I can help you a bit. The inclinometers and compass are internal, not external. From the packaging they look like the old micro-machined strain gauge devices. Here is a photo.

That thing wth the copper coils is the electronic so-so compass

And do you see the two chips just to the right of the coil thing? They are mounted perpendicular to each other. The are the side to side and up down MEMS inclinometers. Here are some close ups.

I'm pretty convinced these are the two chips, but long superceded. Similar ones are readily available.

I mention this in case you'd like to do the inclinometer. Re the temp sensor I happen to be taking apart a prado at the moment for parts and I will try to take note of where the sensor is when we will the dash.

(Sorry I do not have a spare binnacle, before anyone asks. They all die here in the Middle East heat)

 

[pomtom44]

Well, I can help you a bit. The inclinometers and compass are internal, not external. From the packaging they look like the old micro-machined strain gauge devices. Here is a photo.

That thing wth the copper coils is the electronic so-so compass
View attachment 3643488

And do you see the two chips just to the right of the coil thing? They are mounted perpendicular to each other. The are the side to side and up down MEMS inclinometers. Here are some close ups.
View attachment 3643490
View attachment 3643491

I'm pretty convinced these are the two chips, but long superceded. Similar ones are readily available.
View attachment 3643494

I mention this in case you'd like to do the inclinometer. Re the temp sensor I happen to be taking apart a prado at the moment for parts and I will try to take note of where the sensor is when we will the dash.
View attachment 3643505
(Sorry I do not have a spare binnacle, before anyone asks. They all die here in the Middle East heat)

Thanks for the info, I had managed to figure most of that out myself from taking my own unit apart.

I have since gotten an arduino to do 90% of the sensors I am after.
Internal temp, roll / pitch, compas, GPS, etc.

It is just the data from the engine I am trying to get now.
Since I have a older model, there isnt any ODBII ports, only a basic diagnostics port.
Which is why I was hoping to figure out what the obscure "instrument" wire is, and what the data coming from it is, so I can reverse engineer that and tap into it.