Discussion and questions related to the course EFI Wiring Fundamentals
I'm about to make myself a harness from my firewall connector (61 way) to a Motec M130. I'm planning on having all my 5V spliced at the ecu as well as the 0V. I know this will eat up a lot of the pins on the firewall connector, but I think it will make my life easier in the end to avoid potential voltage offsets. I was told it was good practice to segregate the critical sensors (REF/Sync) from the auxiliary sensors, I am just wondering if its a good idea to use the +6V3 Output for the Ref/Sync hall sensors. I assume I can use any of the two Sensor 0V for the +6V3? Let me know your thoughts. This ECU has 6 Analogue Voltage inputs, 4 Analogue Temperature inputs and 7 Universal Digital inputs, so that means I would need 15 5V (if not using 6.3V for ref sync--universal digital input 1 & 2) or 13 if I can use the 6.3 for REF/Sync split between the two 5V available. I would then need 19 0V to accommodate all the digital, temp and voltage inputs. Is there anything wrong with my logic here?
Hi Jean, first up there's nothing specifically wrong with your intention of passing all your 5V and 0V wires through the bulkhead connector but as you've worked out, it's going to chew up a lot of pin allocations. I'll also point out that your analogue temp sensors don't require a 5V supply, just a 0V. If you've got enough spare pins then there's nothing to lose here however I'd personally be inclined to spread the load a little. Let's say you need 8 5V supply wires - I'd be inclined to splice a single 5V into 2 at the ECU header (therefore only using up 2 pin locations in your bulkhead connector) and then splice each into 4 on the far side of the connector. Usually the ECU is going to have more than 1 5V output too, so you can split the load this way. There isn't strictly a right and wrong way to do it and personal preference does come into play.
Provided your hall sensor is capable of operating on the 6.3V output (most are) then this is a good idea.