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Tapping an OEM CAN Bus
Posted: Tue Oct 29, 2024 8:13 pm
by P.S.Mangelsdorf
Over the next few months, I'll like have the opportunity/reason to take CAN logs on a few stock OEM EVs. When I've needed to log in my conversion, I've added a place in the harness to tap the CAN bus, but in these circumstances, I won't have the ability to modify the stock wiring.
What are some good options/approaches to CAN logging with minimal disruption to the harness? Is there a good way to do it that will not damage anything?
Re: Tapping an OEM CAN Bus
Posted: Tue Oct 29, 2024 8:18 pm
by johu
Apparently there are inductive methods but never tried it. If you have enough time you can find the connector with the CAN wiring (VW orange) and see if you find both sides of it for sale. Then make a tap cable
Re: Tapping an OEM CAN Bus
Posted: Tue Oct 29, 2024 8:21 pm
by P.S.Mangelsdorf
johu wrote: ↑Tue Oct 29, 2024 8:18 pm
find the connector with the wiring and see if you find both sides of it for sale. Then make a tap cable
I was thinking about trying this. I know some of the busses are only ever in big connectors though, so not sure how much work it'll be.
I was also thinking about trying to use a needle into each wire of the bus, but not sure if that was crazy.
Re: Tapping an OEM CAN Bus
Posted: Tue Oct 29, 2024 8:25 pm
by johu
CAN busses are surprisingly picky when tapped that way as in you could disturb the bus. But then you can just remove it.
Perhaps penetrating the back of the connector hits more metal? Works well with unsealed ones at least
Re: Tapping an OEM CAN Bus
Posted: Tue Oct 29, 2024 8:43 pm
by P.S.Mangelsdorf
johu wrote: ↑Tue Oct 29, 2024 8:25 pm
Perhaps penetrating the back of the connector hits more metal? Works well with unsealed ones at least
Good point. What have you used to do that? Any specific pin or just a strip of metal?
Re: Tapping an OEM CAN Bus [SOLVED]
Posted: Tue Oct 29, 2024 8:56 pm
by johu
Resistor leads

Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 5:39 am
by arber333
I used scope needle probes from the back of Nissan chademo CAN connector to scoop up telegrams. And it worked well.
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 6:06 am
by RetroZero
I have a couple of Crocodile clips. Tried to get it working, but interference with the bus is all I get.
Parallel scope is by far the least intrusive, just need the right setup. I have a spare Crocodile clip. PM if you're interested....just need to pay postage

. Maybe you can find a solution

Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 7:18 am
by uhi22
pin from the sewing box, they are not very sharp originally, I sharpened them.
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 12:08 pm
by arber333
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 12:10 pm
by P.S.Mangelsdorf
johu wrote: ↑Tue Oct 29, 2024 8:56 pmResistor leads

I've got plenty of those!
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 12:11 pm
by P.S.Mangelsdorf
uhi22 wrote: ↑Wed Oct 30, 2024 7:18 am
pin from the sewing box, they are not very sharp originally, I sharpened them.
I've got a few that are quite sharp and should do the trick
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 12:12 pm
by P.S.Mangelsdorf
RetroZero wrote: ↑Wed Oct 30, 2024 6:06 am
I have a couple of Crocodile clips.
I've use those on my conversion, but had to strip insulation off the wire to get contact.
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 8:49 pm
by RetroZero
P.S.Mangelsdorf wrote: ↑Wed Oct 30, 2024 12:12 pm
I've use those on my conversion, but had to strip insulation off the wire to get contact.
No need to strip wires.

- 1730321231125467284868426578146.jpg (34.45 KiB) Viewed 7090 times
Re: Tapping an OEM CAN Bus
Posted: Wed Oct 30, 2024 10:46 pm
by tom91
RetroZero wrote: ↑Wed Oct 30, 2024 8:49 pm
No need to strip wires.
1730321231125467284868426578146.jpg
Never got these working reliably for me
Re: Tapping an OEM CAN Bus
Posted: Sat Nov 02, 2024 12:08 am
by P.S.Mangelsdorf
Thanks all for the ideas - I'll share if any work particularly better than others. Hoping to do some logging on a friend's Chevy Bolt, and then in a few months the Charger Daytona (STLA Large platform) I just ordered.