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Splices location

Practical Motorsport Wiring - Professional Level

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Hi guys,

Sorry if this question keeps coming back but I'm having more splices than usual and I'm not sure where to put them. The harness will be fully concentric on both sides so I would like your experience on this.

Here it is. 81 wires in total, 61 going to a firewall mil-spec connector.

Now looking at my splices:

-5Va:4 wires

-5Vb: 3 wires

-0Va: 8 wires

-0Vb: 13 wires (crank,cam,knock,wheel speeds on this one)

Would you use an MS3470 24-61S at the firewall and put all the splices inside the branch point of both ECU connectors ? Or, use an MS3470 22-55S at the firewall and put all the splices inside the boot of this connector ? That would mean using 4 pins for both 5V's and 0V's ?

Thanks a lot gentlemen.

There isn't a specific way you MUST deal with this. It's as much down to personal preference and parts cost as anything. Personally I try and keep my splices at the ECU header plugs which in this case would require a bulkhead connector with sufficient contacts to pass all the conductors through.

Thanks Andre

Is there anything wrong with putting the splices on the engine side of the bulkhead connector? Im in a similar situation and if I didn't put it on the engine side then I'd need to rethink my connectors, currently if I splice in the engine side I can get away with a 55 pin connector no issues

Nothing wrong with that. I often do that as long as the connector can handle the total current through the number of pins used for a particular circuit.

I feel like it's weird that say the haltech elite only passes out 1 5v supply wire at the ECU but 3 sensor grounds that are all tied together anyways. Why the weird breakup?

Probably because temperature inputs have internal pullups, so often you need more sensor grounds than supplies external to the ECU.

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