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By JudeWelsh
#195658
I'm an experienced Arduino Uno user and trying to get the CAN bus sheild to report message traffic to the serial output screen for my 2011 Jeep Wrangler (CAN interior bus). I purchased the sparkfun sheild and OBD2-DB9 cable. I'm using the basic Sparkfun library w/o modifications.

I get a message saying the sheild is initialized, and see no message traffic. It turns out for the Jeep, that CAN traffic is not available via the OBD2 diagnostic port. So I hacked the radio cable, and using MOPAR config data, found the correct wires for CAN-H and Can-Low. I spliced them and changed the 3 jumpers on the sheild and soldered a 4 pin header to the CAN header.
I have triple-checked that I have the correct bus wires in the harness.

Still seeing no traffic, in fact, when I hook up both CAN-H and CAN-LOW the Jeep console displays "no bus". I see in CAN documentation that the system is terminated by 120 ohms (60-60 ohm), and I saw a post here on Sparkfun that someone had soldered in that resistance, though didn't mention why. I think somehow the bus is shorting out when I connect it to the sheild. Does anyone have luck with this card?

I was going to try the SKPang blue sheild, though the schematic for the SparkFun product says "SKPang" on it, so not sure if there are differences.

I'm also on a Jeep forum asking the same question...if you have any advice, please let me know. thank you!
By JudeWelsh
#195662
I think I answered my own question. Read the manual - SLOWLY.