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Elite 750 parallel wiring

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Good day everyone,

I have some inquires regarding different wiring setups, i have haltech elite 750 and two looms, i am planning to use 1 ecu on two cars. The first car has standalone setup with no issue, but the second car will have haltech harness wiring with stock ecu, so which wires from haltech to connect with stock ecu? Which sensors to use on haltech and which sensors to keep controlled bu stock ecu?

Thanks in advance

Kapon Kap Dear

So you're intending to run the second car as a piggyback application then? The answers to your questions are going to depend on what your'e trying to achieve. For example you could allow the factory ECU to control aspects such as idle speed or you could let the Elite do it. The way you wire the ECU will depend exactly what you're going to do with the Elite and what the factory ECU is going to do. I guess my next question is what's the application and why are you retaining the stock ECU?

Generally in a piggy back application all of the sensors need to be piggybacked into both ECUs so that the factory ECU is happy and doesn't throw a CEL, and the Elite has the inputs it needs to do its job. One thing to watch out for if you're piggybacking temp sensor inputs is that you need to make sure you've disabled the internal pullup resistor. As for the outputs, you would allow the Elite to control the injector and coil outputs.

Dear Andre,

My apologize that I didn't mention in my post that the engine is DBW which not supported by 750, so i will go for piggyback setup to keep engine happy as much as i can, this is the main issue which restricts me, so now i can share wires ( splicing) between haltech and stock ecu such as : trigger,home,tps,ect,iat. Is this right way to do? Injectors and ignition coils should have fuse and relay? What about haltech power source? From stock ecu also splice on 12v wire? In my previous setup which is full standalone, i did fuse and relay boxes for ecu,fan,injectors,ignition coils. What about piggyback setup in this regard? Thanks Andre for your care

the sensor 5v supply, do you disconnect the oem ecu 5v and use the standalone 5v supply for accuracy. then let the oem ecu run with the less acurate signal? the oem ecu in my case is only used for gauges and keeping the rest of the car happy.

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