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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.
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.
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#:
Here's the pinout for the 2.5mm jack version (couldn't find the 2x2 molex version) if you want to make the cable:
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):
* 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
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.
Code:
:
Serial communication on pins TX/RX uses TTL logic levels (5V or 3.3V depending on the board). Don’t connect these pins directly to an RS232 serial port; they operate at +/- 12V and can damage your Arduino board.
:
The Arduino Mega has three additional serial ports:
Code:
Serial1
on pins 19 (RX) and 18 (TX),
Code:
Serial2
on pins 17 (RX) and 16 (TX),
Code:
Serial3
on pins 15 (RX) and 14 (TX). To use these pins to communicate with your personal computer, you will need an additional USB-to-serial adaptor, as they are not connected to the Mega’s USB-to-serial adaptor. To use them to communicate with an external TTL serial device, connect the TX pin to your device’s RX pin, the RX to your device’s TX pin, and the ground of your Mega to your device’s ground."
I'm using Serial Port 1 for GPS which is connected to a Arduino/RaspberryPi 10Hz GPS daughter board so can hook these up directly (the serial signal voltage from the GPS card will not exceed 5V).
I'm using Serial Port 3 of the Teensy to connect to the Innovate's Serial port using a FTDI Serial ttl-232 adapter.
I'll need to look at my code again to see if I needed to initiate communication with the MTX-L, I wrote the class over a year ago (ie. if I did then the Tx pin is needed, otherwise it's not).
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).
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%.
MTX-L to MSLabs CAN connection
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