Advanced Functions
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Advanced Functions
The App has a special function for advanced users who understand the J1939 and J1708 SAE
specifications. This is located in the System Settings page (Settings/System/Advanced Functions).
Its primary purpose is to check to see if an ECM is sending data for a particular PGN or PID for
possible inclusion into the App. It can also be used to send a PGN or PID to an ECM but you do
this at your own risk and BlueFire LLC is not responsible for any damage done to your vehicle as a
result of the PGN/PID data sent.
To monitor a PGN or PID follow these steps:
1. Check whether you want to monitor a J1939 PGN or a J1708 PID.
2. Enter the PGN/PID.
3. Specify the Source. This is the SAE standard ECM source code. The default is a global
source (255 for J1939 and 0 for J1708).
4. Set the Interval in milliseconds. A value of 0 will return data only when it changes.
5. Skip the Send Data field. This is only used if you're sending data to an ECM.
6. Check 'Request' if this is an 'On-Request' PGN/PID.
7. Check 'Mullti-Packet' if the PGN/PID consists of multiple packets.
8. Tap 'Monitor PGN/PID'.
9. The PGN/PID will be placed onto the appropriate data bus. If the Source is global, all ECMs
will receive it.
10. Data will be returned from the ECMs in the 'Source' and Return Data' fields. If multiple
ECMs respond the data will alternate between the ECMs.
11. If no data is returned then no ECMs are responding. If you're unsure whether this is an
'On-Request' PGN/PID you can try setting that and retrying.
12. The 'Return Data' will be in hexadecimal format and be structured according to the SAE
specification.
If the data returned is 0xFF then it is not being transmitted by the ECM. Note, you need to know
the exact location in the PGN/PID and how many bits the data consumes. In most cases the data
is on a byte boundary so looking for 0xFF in that particular byte(s) is good enough. If the data is
not on a byte boundary (eg. less than 8 bits), then you need to look for just those bits being all
ones which indicates no data. If the data is not 0xFF then it is being transmitted and can become a
candidate for addition to the App.
The easier way is to start monitoring the PGN/PID and take a screenshot of the returned data and
send it to BlueFire Support along with what you're looking for and then it can be determined
whether data is being transmitted and if it qualifies as a future enhancement to the App.
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