I was looking at some of the PIWIS II wiring diagrams for the CAN gateway and saw how the CAN Crash wires essentially branch out from three parent wires into many; it's not clear what mechanism Porsche uses to accomplish that branching. I might dig around in there to see if I can spot where all the orange/blue + orange/brown wires go... but I bet it's super buried and perhaps totally inaccessible without tearing up a lot of stuff.

Has anyone done this or knows off-hand what it looks like...? I know for read-only stuff, there are actually devices that will just wrap around CAN bus wires and pick up the signals without cutting into the wire (!), but for my application, I need write access, as well (the final piece of a PDLS+ retrofit: the front windshield camera for automatic high beams). At the moment, I have only one set of wire taps for the entire project and would like to keep it that way for reversibility/safety reasons, but the CAN bus is a difficult one...

 

I dont know what porsche does for branching, but i came up with a 'reversible' solution for wiring my data logger. I read that using taps was not great for connecting to the can bus, and i wanted a way to disconnect the loggers wires multiple times from the car when not in use without destroying the porsche wiring. I also wanted it to not fail during track use. So i bought my own wires and soldered into the can high and low. The other end of those wires i used posi-twists, to connect to the data logger wires, which branch into a k712 which screws into the logger port. So this way i didnt have to solder the big data logger cable directly to the car, and i can disconnect he logger cable and tuck the remaining wires out of the way.

is your goal to be able to disconnect the module you are connecting to without wearing out the can bus wiring as you might by using wire taps that cut through the insulation? If so, this could be one approach. I wanted water resistant connectors so i went with posi twists. Its been a year of track and autox use including rain and no problems with the disconnects/reconnects and no problems with the logger acquiring data.

Somebody else may have a better solution.

CAN wire -> my wire -> connector <- logger cable <- logger unit.

 

I suppose my #1 goal is durability, and maybe posi twists would be stronger than the 2-way wire taps I've been using. My second goal is to have a fully reversible setup: no trace of cuts or taps, etc., should I want to undo anything. I avoided wire tapping all of the power sources for this project by actually running new circuits to the fuse box; it looks super clean and is fully reversible. The CAN bus architecture is trickier, for sure. (Or maybe it's just more unfamiliar/undocumented, I dunno).

 

I have another project going where I am trying to tap into the CAN Bus without splicing or damaging any wires. The best way I found to do this was using the technique that is used to install the Tech Art or the KW lift kit. They use a series of TE connectors and crimps to make a y-cable that is fully reversible . I purchased just these parts from the kit (cost $350) and I am trying to reverse engineer it by identifying all the connectors and contacts. PM me for more info.

 

Unless you want to make a custom cable like krburrell has done, the Posi-taps work very well with minimal disturbance.

 

Yeah, I reached out to him by PM. I'm very interested in the custom cable idea; wish I had thought of that before I wire tapped two CAN bus connections. But I have two more I need to do, so this would be great!