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wgstatenj avatar image
wgstatenj asked

712 Relay configuration help

Need help trying to config the 712 to auto start my Sprinter engine based on SOC or Low Voltage of my Lithium batteries. Installed Mid City Engineering RV Remote/Auto Start module. If I touch the 2 wires they supply from their module engine starts. When I Connect to NO, Com does not work. I tried default, Charging, etc with no luck. Relay appears to work, but no start on engine. Any help would be appreciated. Notes from Mid City below

Optional start / stop / status out triggers for use with external input (eg: battery monitor with start/stop relay, compressor monitor, temperature monitor & more)

  • Note: when using this auto start with external 1-wire trigger (latched ground to start and run) the system will re-start if ground is still applied to start wire after run-time expiration. The system will continue running and re-starting until external trigger removes ground signal.

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3 Answers
Justin Cook avatar image
Justin Cook answered ·

What do you mean "when I connect to NO, COM does not work"? COM is where you connect IN to the relay, it's not a port that performs work. So in your case (and to be clear, I strongly disapprove of those MidCity Engineering modules) what you'd do is run a simple wire from chassis ground in to COM, and out of NO to your module, since the module is looking for a switched ground wire.

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wgstatenj avatar image wgstatenj commented ·

Appreciate the information. When they installed the module they supplied the pig tail connected from their module. No information provided by Mid City or could I find in their manual. My inexperience, but maybe the wire is coming from a chassis ground but will verify. Any more information on disapproval of Mid City module? Thank you, Wayne

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wgstatenj avatar image
wgstatenj answered ·

Followed your advice on running wire from chassis ground then NO to Mid City. SOC setting when reached, woke up dash as if hitting the push button once but engine failed to start no crank. Drone responded that engine started. What settings/configuration should be on 712? default or Charged, invert, closed time etc. Thank you, Wayne

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wgstatenj answered ·

Issued solved. After getting advice from Sunlight Conversions, ignoring Mid City, simply set voltage to desire setting, using default on relay with the 712, 0 closed time (did not work with 1 minute) it worked. Previous advice about Mid City from Justin or any device that connects to ECU no matter what vendor says will void warranty. Remove entirely, not just valet mode as stated by Mid City. Was at dealer today for another matter and was verified.

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