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Honda CAN protocol


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Hello. I've spent a considerable amount of time analyzing the CAN data for a Civic FD2 in order to retain the stock cluster functionality. Now I can operate it with a G4+ Thunder and without requiring the stock ECU to be present on the CAN bus.

There are some quirks of the Honda protocol that cannot be defined using CAN Manager, so I use CAN Manager to put the bulk of the data on the bus, pick it up with a Macchina M2, do the required transformation and retransmit.

I was wondering if you would be Keen to incorporate this logic into the Thunder directly. This will hold good for a lot of Honda's with CAN driven clusters.

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The only info from the ECU they expect are RPM and VSS. The HDS scanner also expects a repeating VIN frame to be able to connect.

Because no other modules are touched, they remain happy and chatty as usual.

 

There are two major issues here

1. the cluster expects a speedo pulse from the ECU once every 10 meters to keep the odo ticking

2. The last byte of each frame is like a checksum, which must be valid, or the cluster rejects the entire frame and everything goes haywire. I've managed to figure out enough of the logic to have the Macchina compute this byte and keep the cluster alive.

 

Besides these, everything else is fairly straightforward.

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