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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » CANBus sniffing via Telnet and AT and OBD commands.

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Author Topic: CANBus sniffing via Telnet and AT and OBD commands.
danielfbahr
Member
Posts: 19
Post CANBus sniffing via Telnet and AT and OBD commands.
on: October 7, 2019 (GMT)

Hi I would like some feedback on the method I’m using to find the transmission temperature PID on my vehicle which doesn’t have a OBD mode 22 PID for that data.

I know the information is there as it can be displayed on the dash after entering into a hidden “engineering mode”, and I have a scan tool which can access it also.

I found some header information for the transmission control module in my vehicle and wanted someones opinion on the commands I plan to use and my logic in finding the data.

Method:
1) Connect to vehicle via OBDlink MX+ adapter using telnet.

2) Use command AT CRA 18F(CRA-CAN return address, 18F is trans control module header address). This would only monitor data from 18F.

3) Use command AT MA (monitor all messages)

4) Access the temperature read out on my display so it is displaying then record the trans temperature. Add 40 to the decimal to account for the zero offset, Convert decimal to hex.

5) Look for information with Header 18F and the PID data of the trans temp in hex.

6) Figure out PID value from the returned information.

7) Use header of 18F and custom pid to make a custom PID in torque app.

Does this sound like it could work?

moreause
Member
Posts: 440
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 7, 2019 (GMT)

i would say start to monitor all adress

just to make sure that adress is used

sometime value are not coming from where you expect it

if you monitor only one adress tel net is not that bad

if you monitor multiple adress …it harder to figure out
since the value just appear on a never ending list

instead of just a line with changing value

if your a bit mecanic and electrical savy

if you know the ohms resistor of the sensor and have access to the connector on the transmission

you can buy a variable ohm resistor and change value while checking the screen

you turn the key on … engine of so most value are steady
and you start changing the ohms value …. it’s easy to find if it’s there

F-150Torqued
Member
Posts: 420
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 7, 2019 (GMT)

QUOTE “you turn the key on … engine of so most value are steady
and you start changing the ohms value …. it’s easy to find if it’s there”

_THAT_ my friend, is ingenious. Down her in ‘south Texas’, we call that one hell of a good ‘red-neck’ techinque.

—————————–

54371019

danielfbahr
Member
Posts: 19
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 8, 2019 (GMT)

Quote from moreause on October 7, 2019
i would say start to monitor all adress

just to make sure that adress is used

sometime value are not coming from where you expect it

if you monitor only one adress tel net is not that bad

if you monitor multiple adress …it harder to figure out
since the value just appear on a never ending list

instead of just a line with changing value

if your a bit mecanic and electrical savy

if you know the ohms resistor of the sensor and have access to the connector on the transmission

you can buy a variable ohm resistor and change value while checking the screen

you turn the key on … engine of so most value are steady
and you start changing the ohms value …. it’s easy to find if it’s there

Great idea thanks for that. I had a bit of play with telnet for the first time today connected to the vehicle and I think you’re right monitoring all info would be the way to go.

cintakc
Member
Posts: 1307
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 8, 2019 (GMT)

give detailed information about your car

Capp777
Member
Posts: 2709
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 8, 2019 (GMT)

Cintakc;

The OP posted another thread which
includes some of the info you seek…

https://torque-bhp.com/forums/?wpforumaction=viewtopic&t=14046.0

danielfbahr
Member
Posts: 19
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 11, 2019 (GMT)

Quote from cintakc on October 8, 2019
give detailed information about your car

2009.5 Holden VE Calais V Wagon 3.6 V6 5 speed auto 5l40e.

The VE commodore was soled as a Pontiac G8 in the USA.

A Calais is an upspec commodore.

I suspect my vehicle is not fully compliant with the standard CAN protocol for a lot of the extended mode 22 pids.

When I do a scan for PIDS it looks like all of the results come back the same, -1 decimal.

7EA037F2211 if I scanned header 7E2

The hex response is 7E8….. if I scanned 7E0, but also all the same -1 decimal.

I figured out how to sniff the can bus with telnet, but I think the bluetooth is to slow to keep up with all the info and keeps stopping.

https://drive.google.com/open?id=1zAjEls3i6s0qvjrNUTBN-Y0swcfDB1Tr

danielfbahr
Member
Posts: 19
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 11, 2019 (GMT)

I think it might be coming back with all the null pids.

There just too many pids to go through and try to get data.

I’ve tried using pids from the 19– range but nothing.

When I went back and read the info for more bluetooth adapter the OBDLink MX+ it indicated that it couldn’t read extended live data for GM vehicles even though it can talk to SW CAN.

I know mode 221940 works with the V8s and the series 2 V6s I think I’m unlucky and in period prior to all of the extended PIDS being written for mode 22.

I can see it on my scan tool with holden specific software. It annoys me the information is in there I just can’t get to it.

cintakc
Member
Posts: 1307
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 11, 2019 (GMT)

try another scan with Header 7E1, DA18F1, DA19F1

danielfbahr
Member
Posts: 19
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 12, 2019 (GMT)

I’ll have to give that a go.

Prior to now I have tried entering PID 221940 with headers 10F1 and 18F1 as I know GM/Holden used those headers on their VPW can.

Interestingly the response wouldn’t stop unless I terminated it and it would trigger a traction control and ABS warning on the dash!

cintakc
Member
Posts: 1307
Post Re: CANBus sniffing via Telnet and AT and OBD commands.
on: October 12, 2019 (GMT)

Prior to now I have tried entering PID 221940 with headers 10F1 and 18F1 as I know GM/Holden used those headers on their VPW can.

Header da18f1 for protocol ISO15765-4 29/500

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