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Hi Guys,

Need a little help setting up the G4+ to receive some data from a Compushift Transmission controller.

Adam you helped me with this through facebook, but didn't seem to receive anything, so wanted to make sure I'd done it right or we have the right settings.

In the facebook post you gave me the following settings





But using these settings I didnt get anything received on CAN DIG #8

Now I had a look at the HGM Compushift Wiki and they have the J1939 CAN spec in Excel format.
The CAN function I want is



Looking at the ID, translating the HEX to dec is 15729152. So is this the correct ID or 217055998? Also having trouble understanding/translating the Signal Byte and Bit.. See you have overlay-ed the numbers for it but how come it seems to go backwards? If somethin in J1939 was on Byte 2 Bit 2 Width 2 would that be Start 21?

Also the TCU has accelerometers (X,Y,Z) and also available on CAN. Is it possible for the Link to capture and log these?




Thanks greatly in advance for any advice.



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I think the ID 217055998 is still correct as their document is missing some of the ID.  

But looking at that DBC file again I do see one possible issue, I think we should be looking at byte 0, not byte 1.  So leave everything else the same but try changing the start position for CAN DIG 8 to 3.


7 hours ago, wastegate said:

Also the TCU has accelerometers (X,Y,Z) and also available on CAN. Is it possible for the Link to capture and log these?

You could receive them as CAN analogs but they are not all that useful in G4+ as you cant apply filters and units etc to a CAN input.  

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Hey Adam,

I gave Byte 3 a go on both ID 217055998 and 15729152 but didn't get anything during a gearchange. I also tried Byte 11 for giggles on both IDs and nothing as well. I've attached by config and log just incase you would like to see it. But will reach out to Guy @ HGM and see if they can help too.



Log 2020-10-4 12;12;09 pm.llg Scott's Map 07052019 - Flex Tune - Nick edit 04102020 - cold start better - new VVTI map WIP - Elite Gauge CAN - Cruise Changes - base fp 3bar - Accel Enrich - Idle Ign - IAT Fuel off.pclr

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I just had a quick look at their wiki myself and the ID is different than the excel screenshot you attached earlier, It has the C on the front.  There is also a note that you may have to place a 3 where the x is, but that doesnt look right to me so try it without first.

Try the map attached.  Watch CAN Dig 7 & 8 as I have put one in byte 0 and one in byte 1.



Try this1.pclr

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  • 2 weeks later...

Just to update, as things get confusing, managed to capture some data. Still working on getting the shifts transmitted but it's certainly in HGMs court now, likely need a input shaft speed to the controller as well to know when it's starting the shift.. They wrote a custom firmware to bypass this but still not getting anything on the shift.

I am getting the following though which just shows something is getting through.
Using Receive CAN ID 217055747 (CF00203) I got from Guy @ HGM
Start Pos 5, Width 2, LS, Unsigned = Torque Convertor Locking Up
Start Pos 7, Width 2, LS, Unsigned = Gear Engaged (Shifting from P to D etc)

From the data HGM supplied, looks like the Shift should be on Start Pos 3 in the Link. Not logging anything on that bit so will see what HGM come back with. They have been more than helpful to try and get it working.


HGM CAN1.png

HGM CAN2.png

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  • 2 weeks later...

Update, HGM fixed the firmware and now have gear change request. 

Thanks Adam on the torque reduction strategy, works a treat. Just need to fine tune it. I've reduced the IGN trim retard a little as I don't have 20 degrees of timing in some spots and it's getting retarded too much and seems to spike boost. 

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  • 3 months later...

Sorry for the late replay @Adamw, yes getting that data on CF00203. Input shaft speed is listed at HGM CAN Byte 6 bit 0. Which to me looks like Link Start Pos 47, LS, 16bit length.

I've been going through the CAN messaging and doing a bit of a spreadsheet 


I'm really not sure why HGM decided to use the full HEX for frames egress but you need to drop the "C" for frames ingress to the CS3. For example in order to give the CS3; RPM and TPS you need to set a transmit channel to DEC ID 15729664 (from their docs) which is HEX "F00400" but egress frames from the CS3, you NEED to add "C" to the HEX ID to get CF00203 and thus DEC ID 217055747.

I will test the shaft speeds out when I get my car back as wife stole it today. Can't do much with it on my G4+ but I have my G4X setting on my desk waiting and already put it in the config.


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  • 2 weeks later...

Hi Adam,

I'm just trying to get the Gear Shifter Position from the TCU to the G4+, I have Gear working (showing 1-4) from the TCU, I have the G4+ looking at the byte 6&7 as it's 16 bits on the same ID as Gear. Thing is the TCU is outputting ASCII, but the g4+ only wants numbers? I noticed that the 350Z plug is setup for GSP over CAN too and that seems to be working. Is there something I'm missing?

Attached PCLR



Scott's Main Tune - Nick mods 13022021 - Multiplex CAN.pclr

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