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Newbie Question Related to Standalone ECU Communicating with Gauges

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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I'm building at Triumph Spitfire powered by a Toyota 3SGE Toyota Beams Blacktop with a LINK MonsoonX ECU https://panicmade.com/wiring/p/universal-beams-kit with New Vintage CFR Gauges https://newvintageusallc.mybigcommerce.com/cfr-red-6-gauge-3-7-16-kit/ .

I'll say at this point I've never taken on a project of this level customization before, and I chose this gauge style over more obvious choice of a digital dash mainly to match the style of my build. In this case I did not "look before I leaped" and planned to figure out how to make the sensors/ECU talk to the gauges at a later date. I'm now approaching that "later date" and need some help figuring this out.

I am vaguely familiar with CAN technology and think this is probably part of the solution, but again I am a newbie when it comes to this. I would appreciate some advice and/or have some one point me in the right direction to help bring me up to speed on how best to make this configuration work.

Thank you in advance for your input!

That instrument pack is designed for older vehicles and/or a "stand-alone" setup. It uses its own senders and control logic.

The only tie-in with your ECU is the need for a tachometer signal, if I read the installation guide correctly.

There are gauges available that will run off a CANBUS, but you may need to check the ECU and gauge manufacturer's support for compatability.

I'm seeing what you're seeing Gord. Rick there doesn't seem to be any ECU setup required here, other than the tach output.

Gord, I understand these gauges are stand-alone but the senders on the 3SGE go straight to the LINK ECU? How do the gauges get the signal? Do I spit the signal to go to both the ECU and the gauges? Forgive my ignorance on this.

I think I can handle the tach output with this https://newvintageusallc.mybigcommerce.com/cansync-obd-interface-speed-tach/ from the same company.

Easiest thing is to simply use a second sender unit for the gauges - they're even supplied, there are often secondary ports on the engine, or a "T" piece can be used. This was commonly done in the earlier days of EFI, before everything was as integrated as it is nowadays.

Off hand, the only place this doesn't seem practical is the fuel sender?

I'm not familiar with the ECU, but if it has analogue outputs, you may be able to set those up if the voltage range is sufficient - anyone?

Give the company that made the instruments a call, or e-mail, to see if they have a simple fix, or workaround, such as you suggest might work?

Personally, being old, I do prefer dials to digital read-outs, and have made a note of their lines in case I have an application that would work with them.

There was mention of this problem from around 28:00 onwards - might be something you can follow up on - https://www.youtube.com/watch?v=IWHvQxJqHoQ

I've used some extra outputs from ECUs to run gauges gauges. Some gauges can be run from a PWM signal, that will simulate a resistance based sender well enough, as long as the gauge doesn't pull too much current. You will have to verify this. I don't know if your ECU is capable of this, as I haven't used it. But on other ECUs, such as the Megasquirt MS3X/Pro, there are generic PWM tables that can be set up to use virtually any input as the axis, and then the WM out can be based on that input.

That being said, using a T for the oil pressure is easy enough, the coolant temp sensors/senders you really want to put in the flow of coolant and using a T-can make the reading incorrect, especially if the T is installed in a way that might trap some air. The fuel level sender, if you have that going to the ECU, really can't be split, and would really require a separate sender, or feeding the signal through the ECU as I mentioned above.

Resistance based sensors and sender really can't be split between two devices and still have accurate readings, at least not without custom calibration of both units, that will be interacting with each other on the sensor/sender signal wiring. I've not come across anyone that has done this successfully, especially with gauges, where they are typically factory calibrated, with no user adjustment to them.

Link's PWM tables and frequency settings are capable of controlling a gauge, but as Chris mentioned the Link Aux outputs (ensure you're using a PWM capable output) are limited to 2 amps. The gauges linked look new enough that I'd be surprised if they pull more then a few mA.

Second sensor is the easiest method.

You can actually split a signal between 2 devices, provided only one has a pull up resistor. This is a reasonable common practice when doing parallel standalone installs on factory ECU's, I have done this on toyota's. Caveat is confirming the calibration (voltage vs temp) is correct in the Standalone's table as it may use a different pull up then the factory ECU. Link doesn't allow you to disable the pull up on their AN temp inputs, but if you use a normal AN volt this can work.

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