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5V sensor supply strategies

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I've been looking at setting up another ecu recently and I have never really thought ahead with 5V supply on my car, it's just happened in the working mess it is.

Say you have 2 5V supplies from the ECU, A and B, and matching sensor grounds. Anyone have some strategies or ideas on what is a sound way to distribute it to the sensors?

For example, say you could put everything engine related on A and anything vehicle/driver related on B.

A could have TPS, MAP, Oil pressure, Coolant pressure, Fuel pressure

B could have Brake Pressure (front and rear), Steering angle,

Or is better to have some of the critical sensors on separate supplies? I assume there are many ways to do this, each with their on merit.

Given the opportunity, I put everything critical (and only the critical sensors) on one power supply. Usually this is just Cam/Crank and MAP and/or TPS. Those have critical changing values and the engine can't really run with defaults in the case of a sensor / power supply failure. The other sensors you mention, temps, pressures can all have reasonable defaults allowing the engine to run, but perhaps not a peak performance.

I follow a similar strategy to David, I try and put all the engine critical sensors on one power supply, and the less critical items on the other.

A related situation I encountered was wiring in some Izze Racing tyre temp sensors, which require a 5v supply, but communicate over CAN. Their current draw was relatively high, and by the time you power four of them from the sensor supply circuit of the ECU, you're almost up to half and amp of draw, which is pretty high for a sensor supply. Izze came to the party though and supplied an external 12v -> 5v regulator in a nice motorsport applicable package.

Depending on how many 5v supplies you have, it can be nice to separate digital signal sensors from analogue signal sensors, as the digital switching can introduce noise on the sensor supply line.

Ok, thanks for the replies guys. Using the existing loom, so I'll have to check where the crank and cam signals get power, it's not obvious on the information I have.

Another random thought on the this topic - splicing the supply voltage to multiple sensors - do you guys find it best to run a bus, like the connectors below, or is it general practice to splice them into the actual loom? From all the actual motorsport stuff I have seen, there never appears to be any bus used, but it does look like a convenient way of doing it.

Hi Shane

Nice terminal block with connector , could you share the brand or a web to look for, very useful ...

Also keen for a link to those bus connectors, very interesting!

To answer your question though, I usually splice out a single 5V supply wire right behind the ECU connector to the number I need. This picture should give you an idea of what I mean:

Sleuthed out those bus connectors, cool shit!

Thanks for the link Zac !

Yeah, sorry for the late reply but we get them from Ionnic. Be nice if Deutsche did them for DTM connectors, but using the DT isn't too bad. Seem like they'll come in handy.

Zac, thanks for the picture, very neat way to do the splice.