MTX-L to MSLabs CAN connection
 

The short version is I either need to either find a place to buy this cable, or to understand how to replicate/replace it on my own. Last year I did a dumb and bought a used Innovate WBO2 sensor back when I thought I would never Megasquirt a Miata. Unfortunately, the PO of the o2 sensor forgot to include the cable circled in red - 4 pin Molex to DB9 Serial.

https://cimg4.ibsrv.net/gimg/www.mia...59f95bd676.jpg


I am having issues setting up this wideband to work with the (also used) MSLabs MS3 I just bought. The gauge indicated and Tunerstudio indicated lambda values do not match. I'd like to skip trying to make the analog 0-5v signal play nice, and just plug into the CAN module which is supposedly much better. What I have is below.

https://cimg6.ibsrv.net/gimg/www.mia...76dc0b203a.jpg

The CAN module was wired for an AEM wideband, which just needs a single blue wire hooked up per MSLabs instructions. My Innovate has a 4-wire connection, including a blue wire. Are the other three wires needed for CAN communication, or are they for communicating with a laptop PC? If not, I'll just wire it up like an AEM and move on with my install.

Of course, the only replacement cables I can find online are for 2-wire Molex to DB9, or 2.5mm audio jack to DB9. Outside of begging Innovate, anyone know of a place I can buy a replacement cable?

Making the cable from an old serial cable isn't a hassle but finding the correct 2x2 plug and pins is harder (ie. you need to buy them from a specialist electronics store).
If you have them great!
If not, you may simply want to buy the cable from Innovate or eBay - here's the part#:
https://cimg6.ibsrv.net/gimg/www.mia...9371fe88aa.jpg

Here's the pinout for the 2.5mm jack version (couldn't find the 2x2 molex version) if you want to make the cable:

https://cimg7.ibsrv.net/gimg/www.mia...f4eeb00fe1.jpg

And, since I'm such a nice guy, here's how to connect the serial cable to the 2x2 plug (view is looking INTO the 2x2-pin plug):
https://cimg1.ibsrv.net/gimg/www.mia...8d82d94438.png
* First line is function
* 2nd line is the corresponding TPS connection from the previous diagram
* 3rd line is the DB9 serial pin
* 4th line is the original Innovate wire colour

3840 is a number I've come across a lot when searching, but it's very frustrating to see a , and somewhere else a 2.5mm cable end, all while searching for the same part number. It's made me a bit hesitant, perhaps overly so.

When I punch in a google search for "Innovate 03840", the link to Innovates own site is dead.

I think I'll take the plunge on that eBay listing. Thanks for the feedback and sanity check!

The pinout is helping me a lot. Thank you. I want to build a Can- Converter myself and i am looking for information from the used protokol.

Is these still the used one?

http://www.innovatemotorsports.com/s...eriallog-2.pdf

Yep, that's the one I used (see post#9 of https://www.miataturbo.net/megasquirt-18/megasquirt-dash-insert-gauge-96229/ for details).

Dude you are a fucking Genius. That dash looks amazing :eek4dance

I have no access to my car till next week. Would be nice if you can help me out so i can order the parts.

I didn't find anything about the Voltage on the Rx / Tx Pins. Are they +- 3-15 Volt like RS232 or even direkt connected with a 0/5 Volt Uart?

Do i have to connect the Gauges Rx Pin if i do not use daisy chain? On my understandment the Gauges just sends Data packs in 8 Mhz on startup.

From the internetz:
"By the RS-232 standard a logic high ('1') is represented by a negative voltage – anywhere from -3 to -25V – while a logic low ('0') transmits a positive voltage that can be anywhere from +3 to +25V. On most PCs these signals swing from -13 to +13V."

From https://www.arduino.cc/reference/en/...cation/serial/ (read this page if you're using an Arduino):
"All Arduino boards have at least one serial port (also known as a UART or USART): Serial. It communicates on digital pins 0 (RX) and 1 (TX) as well as with the computer via USB.

Thanks again Lokiel. I ordered new Max232 for the communication so i can start next week. First i will start feeding the MS with more Sensor values and later i will make Outputs on my dash.

How do u get your fuel level? Do you read the sensor and display it?

My instrument cluster's fuel sender wire now goes to my board's Analog I/O and I display the value calculated for it (I don't yet send it to the MS - yet).

See Megasquirt Support Forum (MSEXTRA) ? Fuel Level Sensor (View topic)for the circuit needed.

I'm at work now so can't tell you the specific pull-up resistor I used.

l mapped the voltage read to a fuel level % (this voltage will depend on your pull-up resistor) based on the full/empty voltage values for my MSM's fuel sender (took a bit of Google searching to find these).
I double checked these with the actual gauge and they're close enough.

FYI: When I plotted the voltage values reported vs fuel level using the actual gauge, it was almost 2 linear lines, from empty to half was almost straight and from half to full was almost straight - they had slightly different gradients. I took into account both gradients but you could simply use a single one from 0 to 100%.

It is working. There is no need to trigger. The MTX-L starts broadcasting after start.

Thanks again Lokiel