A Digital Dash for Your MegaSquirt MS3-Pro, the RDM-7

Running a MegaSquirt MS3-Pro? The RDM-7 has a built-in preset for it. Pick MegaSquirt MS3-Pro in the setup wizard and the channels come up named and scaled.

Setting it up

MegaSquirt does not broadcast on CAN by default, so one setting has to change before a dash of any brand will see anything.

• Enable CAN broadcasting in TunerStudio. Until you do, the ECU is on the bus and saying nothing — which looks identical to a wiring fault and sends people chasing the wrong problem.
• Set the CAN baud rate to 500 kbps.

The RDM-7 detects the bitrate in its first-run wizard and stores it, so once the ECU is broadcasting at 500k the dash follows.

On an MS3-Pro, CAN High and CAN Low are on the white connector. Confirm the pin numbers against your own MegaSquirt documentation before you cut anything — they differ between MegaSquirt variants and we would rather you checked than trusted a web page.

While you are in there

Check your bus termination. A CAN bus wants 120 ohms at each end and no more. With the power off, a meter across CAN High and CAN Low should read about 60 ohms on a correctly terminated bus — two 120 ohm resistors in parallel. Read 120 and you are missing one; read very low and you have too many. It is a thirty-second check that saves an afternoon.

What the install takes at the dash end

Four wires: 12 V switched ignition, chassis ground, CAN High, CAN Low. Fuse the 12 V at 2 A. The plug is an eight-way push-in terminal block with release tabs, so there is no crimping. The dash ships with a 30 cm harness and a 2 m lead terminated in Deutsch DTM-4.

What you get

800x480 IPS touchscreen, around 50 fps, under 20 ms from bus to screen. Up to 128 CAN channels. Logging to microSD at 1 to 200 Hz in plain CSV, so it opens in Excel or Python. Build your layout in a browser tab on your phone over the dash's own Wi-Fi. Free firmware updates, no licence, no subscription.

Display, logging and CAN transmit only. The RDM-7 does not tune your ECU.