awew911

Have my AIM mxl2 hooked up to the ecu and see the Fuel tank level channel but there is no value. It's a 2009 cayman. Do I need to hookup an iron canyon fuel sensor? If so, anyone know the min /max ohms for the fuel level sensor?

Thanks for the help!

pmason

Can't say for the Cayman but I used the iron canyon sensor for my miata and I drained the tank, put a gallon in at a time and recorded the reading, then made a custom sensor I think and mapped the readings to gallons.

awew911

Yep... That's my last resort. Just want to make sure I'm not missing anything obvious.

Beantown Kman

Your car should pick up fuel level from the ecu. Make sure you have the Siemens ecu selected.

awew911

Correct. Have the Siemens ecu selected. I'll post pics with setup and values shortly.

Thank you!

RickBetterley

I also have a 2009 Cayman S and an MXL Pista (older than your model) and it picks up fuel level fine.
Not sure how I can help but glad to look at my setup and compare with yours.

awew911

Thank you!

I believe I have solved the issue.

With my seating position and steering wheel diameter, the wheel was blocking my shift lights. So I removed the instrument cluster and set the MXL2 further back.

Evidently, the DME doesn't like not having the instrument cluster. Once I plug in the instrument cluster, the Fuel Level feed works.

I'm going to hook up the PIWIS to the car and disable the Instrument Cluster and see if that keeps the DME from erroring out.

I see other cars without the instrument cluster and assume they've just disabled it.

I should have that done this weekend. I'll post the results, but I believe that is the case.

Thanks everyone for all the guidance.

awew911

Got it setup... So full is 10 ohms, empty is 300 ohms. Didn't have a 300 ohm resistor, so used a 1k resistor and set it up as an Up resistor.

From Channel 2 Binder 719, connected GND to one wire (pin 24 on the instrument cluster connector) and to the other connector (pin 25 on the instrument cluster connector) and the channel 2 white (+ signal) together. Took those two wires and connected to one side of the resistor. To the other side of the resistor, I connected the +5v from Channel 2. This puts around 500mA through the circuit. The voltage at the MXL2 was 126mV up to 2790mV. This will change depending on the size resistor. Ideally, I would have used a 300 ohm. Now I need to dampen the signal.

Create a new Custom Sensor:




I had my tank sensor connector to Channel 2, so I enabled that in my MXL2 configuration and linked it to my new sensor:




I then added it to my Display:



I then set an alarm at 4 gallons to give me a warning. Once I size the capacitor to put across the ground to the signal, it should dampen the measured voltage. I'll update here once I get the right capacitor sized.

awew911

BTW - Disabling the Instrument cluster did nothing. The two wires to pins 24/25 on the cluster connector are directly from the tank.

ProCoach

Nice! This helps a lot of folks! Thank you!

awew911

My pleasure. Happy to help. Here's a little diagram showing the physical config.

I'll post capacitor values that work and adjust the diagram...

awew911

This is what the resistor looks like in the tank:


Thick film multi-layer circuit on an Aluminum Oxide substrate. Has trimmed resistors (see laser scribes) that more than likely set it to a linear representation of tank status, even though geometry of the tank is not uniform, top to bottom.

Matt Romanowski

Very nice share. This is great info and the diagrams are perfect for helping people to be able to set cars up.

awew911

Modified the circuit with a different resistor and added a 47 microFarad capacitor to dampen the movement of the float in the tank... Have a breadboard coming in and going to build a small 'box' to package. I'll confirm the numbers once I have it all built out tomorrow...




Now if we can only figure out oil level from the pulse signal on pin 11.

jwasilko

Were you are of http://www.ironcanyonmotorsports.com/icm-fuel-sender/ ?

It's basically what you're building, already built :-)