Advice on wiring ShiftX3, ShiftX2 and MegaSquirt

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Advice on wiring ShiftX3, ShiftX2 and MegaSquirt

Post by davef_dci »


We run RaceCapture MK3 and an Android tablet for display. Previously we were running off of a Chrysler ECU and all inputs to the Race Capture for sensors were coming in via a manually created wiring harness and discrete input wiring. We were also running a ShiftX2 and this was also wired in via the molex harness in the back of RaceCapture and was our only Canbus device.

This year we are converting to using MegaSquirt for our ECU. Our intent is to bring all senors (H20 Temp, Oil Temp, Oil Pressure, Trans Temp, Trans Pressure, RPM, Wideband O2) into MegaSquirt and then pass them to Race Capture via CAN bus. We have also purchased a ShiftX3 - and would ideally like to run this alongside our ShiftX2 for some other display capabilities.

So we're going from having one CAN device (Shift2x) to having three (MegaSquirt, Shift2X, Shift3X.

I'm pretty novice in using CAN, having only used Shift2X. I could use some advice on tackling the wiring initially so I don't make mistakes.

Can all three devices (MegaSquirt, ShiftX2 and ShiftX3, share the same CAN Bus?

Is there an advantage using the Molex Connector versus the RJ45 with splitter(s)?

How do I "address" the ShiftX2 and ShiftX3 so I can use both simultaneously (if this is possible)?

Can I power the RaceCapture and both ShiftX2 and ShiftX3 via input power from MegaSquirt? Can this come in via the RJ45 or should it be run in via the molex?

Any other advice would be greatly appreciated!



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Post by davef_dci »

Bumping this - any guidance for me on this? As a reminder - trying to run ShiftX2, Shift X3 (via CAN2) and MegaSquirt (via CAN1).

Please see the attached wiring diagram.

Does this make sense?

I also need some help on the jumpers. I'm assuming I would cut the terminating resistor jumper on the ShiftX2, correct?

Also, I understand I need to cut the jumper to move the default CAN base address from 931328 (0xE3600). I know I can change it by breaking the trace bridging the ADR1 jumper on the bottom of the ShiftX3 circuit board

Once I cut this trace, how do I distinguish between commands to the ShiftX2 versus the ShiftX3? In other words, If I want to turn on an LED on the ShiftX2 - how to I distinguish this from the same command that would turn on an LED on the ShiftX2???

Thanks for your help!
ShiftX wiring.png
ShiftX wiring.png (204.4 KiB) Viewed 20 times

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Post by brentp »

Hi Dave, you have it pretty close to correct. Placing ShiftX2 and ShiftX3 on CAN2 while having Megasquirt on CAN1 is a good plan.

Here are some suggestions:

* Keep ShiftX3 on the primary CAN ID (don't cut the jumper)
* Place ShiftX2 on the secondary CAN ID (cut the jumper)

With ShiftX3, control it with the built-in firmware support. With ShiftX2, you will need to discretely control in Lua by sending it CAN messages directly. The built-in firmware support for ShiftX2/3 introduced with firmware 2.15.1 focuses on controlling just 1 unit, which covers 99% of installed use cases, and keeps things simple.

We have it further documented here: ... of_ShiftX2

Hope this helps!
Brent Picasso
CEO and Founder, Autosport Labs
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