Inputting CAN

[S172]

Hi guys forgive my thickness already but I was wondering how to or is it possible to input say this CAN data as pictured into a fury and then try to test up the original factory dash this is a OEM CAR up to temp and only has revs and ect working off CAN I pulled this through the obd can at birate 250000

regards 

Scott 

 

[Adamw]

I think you might be looking at the diagnostics comms rather than the actual ecu comms to dash.  The ECU stream would more commonly be 500K, and I would expect to see more ID's.  It is not always on the same bus as the OBD2 port.

Typically the way you reverse engineer the bus is isolate as much as you can, then vary one measured item and watch what changes in the data.  For instance for your coolant temp, you would test with engine not running (so there is less data moving on the screen), fit a potentiometer in place of the temp sensor and vary the resistance - you should then be able to see which byte(s) of data is varying as you change the temperature and also if multiple bytes you can see which is the MSB/LSB and the max and min range.  Once you know where the data is, then you can plug the sensor back in and put it in ice and boiling water to get 2 known calibration points so you can work out how the data is scaled.  

What model car?

[S172]

The car is a 2003 mk2 Clio 182 with very simple CAN system on it I tried sniffing the can at 500k through the obd but it will not talk to it I’ve tested my kit on some other cars and yeah 500k works fine as you said but on this it wouldn’t connect until 250k was sync with my obd2can I’ve got a video of what you said lots of ids changing then settle to maybe five and then just ignition on this is the information I was wondering can i not input on I’d just to see if I get a change on my dash on the temp gauge ? Had limited time with the vehicle as I’ve hard wired mine 

[S172]

This obviously the a screen shot of the video I recorded with running engine as the video even cropped is to much to up load  

[Adamw]

Share your video with onedrive or google drive etc.

[Adamw]

Looking at wiring diagrams online it looks like the engine ECU isnt connected to the same bus as the OBD2 socket.  The ECU CAN connects to the "passenger compartment computer" (this maybe the dash?), and the OBD2 socket connects to the passenger compartment computer via a 2nd bus - so this is a gateway device.  You will need to connect your sniffer directly to the ECU CAN bus if thats what you want to duplicate.  ECU pin 27 is CANH and 57 is CAN L. 

[Loic]

Hi S172 and Adam,

I have contacted a friend who has already done it but not with a link ecu.

the bitrate is 250K

Coolant is in message 0x77A it is  transmitted every 100ms you must transmit your temp +40 °C in the first data BYTE of the CAN message.

RPM is in message 0x0FA it is transmitted every 10 ms in 2 BYTES you must transmit your RPM*8 in the first 2 data BYTES of the CAN message.

if you can send your project I might be able to set it up.

 

[Adamw]

Ok if your freinds info is correct then the settings below would be how to set it up.  Your original screenshot doesnt show any ID's 77A or FA though.

Note you will need to be connected to the ECU part of the bus, not the OBD side.

 

Set up channel 1 & 2 like below:

 

Set up stream 1 & 2 like this:

[Loic]

4 minutes ago, Adamw said:

Ok if your freinds info is correct then the settings below would be how to set it up.  Your original screenshot doesnt show any ID's 77A or FA though.

Note you will need to be connected to the ECU part of the bus, not the OBD side.

 

Set up channel 1 & 2 like below:

 

Set up stream 1 & 2 like this:

Hi adam i think for the coolant the offset is +40 and not -10 and if my memory is correct he told the data type should remain signed 8 bit and not unsigned S172 will have to test both.

Best regards

 

[Adamw]

The coolant temp in G4+ is stored with +50 offset applied, so this is why it needs -10 for the output.  Signed 8 bit with an offset of 40 would only give you a max temp of 85deg so I highly doubt it is signed.  

[Loic]

6 minutes ago, Adamw said:

The coolant temp in G4+ is stored with +50 offset applied, so this is why it needs -10 for the output.  Signed 8 bit with an offset of 40 would only give you a max temp of 85deg so I highly doubt it is signed.  

Ok for the offset i was not aware of the +50 internal offset now we will wait the confirmation of S172.

[Loic]

22 hours ago, Adamw said:

The coolant temp in G4+ is stored with +50 offset applied, so this is why it needs -10 for the output.  Signed 8 bit with an offset of 40 would only give you a max temp of 85deg so I highly doubt it is signed.  

Hi Adam, I have found the info so it is the temp - 40 °C that is transmitted this is why it needs to be signed

so I assume the offset will be -90 and type signed 8bits.

[Adamw]

Unlikely.  Why would they use an offset if they are signing it?  Typically you either use a signed byte or you use an offset, there is little reason to do both as they are both different techniques to achieve the same outcome - the ability to read temperatures below zero.  Set it up like I said originally and see what it reads.  If it really is signed it will still read correctly up to about half way and then will do a big jump and start going backwards.

[S172]

Thanks for the help guys just a quick update I’ve managed to reverse engineer some bits in the last couple of days I found on my model mk2 Clio 172 cup no abs no traction etc I found the rpm on I’d 711 - 1905 on the link with the set up as follows just currently working to get the temp gauge operational I don’t completely understand the bytes and signed etc lol every days a school 

 

[S172]

Right guys just tried the Ect set up with both offsets and signed and in signed nothing appeared to work unfortunately I was wondering if of various models they possibly change the ids depending on spec as my rpm I’d is on 1905 and then I set up the OEM Ecu powered up with a rheostat as the ect sender whilst connected to the obd 2 and found that 77A would appear when I connect the stat and only FA was permanent and when operating it did move my temp gauge now I’ve connected my link up to the CAN before the BCM so it only goes to the dash and obd2 

[Loic]

7 minutes ago, S172 said:

Right guys just tried the Ect set up with both offsets and signed and in signed nothing appeared to work unfortunately I was wondering if of various models they possibly change the ids depending on spec as my rpm I’d is on 1905 and then I set up the OEM Ecu powered up with a rheostat as the ect sender whilst connected to the obd 2 and found that 77A would appear when I connect the stat and only FA was permanent and when operating it did move my temp gauge now I’ve connected my link up to the CAN before the BCM so it only goes to the dash and obd2 

Ok nice to know the rpm is working if you could post a video of the frames when you move the value of the reostat it could help understand and also tells us on the dash what is the current value knowing that the bottom side is around 50°c if my memory is correct and the middle is approximately 90°c

[S172]

Yeah will do the only problem is when I put the I’d into the link with Ect mode set 77A /  1914  I haven’t got anything to operate on the dash temp gauge but I’ll set up the CAN sniffer and the stock Ecu again and video it guys what’s the best platform to send videos over on here obviously chat forum hasn’t space 

Scott 

 

[Loic]

17 minutes ago, S172 said:

 

If you want you can send it by WhatsApp or Messenger i have pm you my name

[S172]

Yeah cool WhatsApp me

scott 

Edited October 31, 2020 by S172
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