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How to wire hall sensor to work with Nissan 240sx OEM speedometer

Practical Motorsport Wiring - Club Level

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Hi guys, i have a 1jz/r154 with an ECUmaster EMU and I'm trying to get the speedometer to work on a Nissan 240sx s13 OEM cluster.

My question is to do with the speed sensor signal:

Originally, the speedometer takes the VR speed sensor signal and outputs a square wave to the ECU. The speed sensor in the 1jz is a Hall sensor and is wired directly to the ECU instead of through the cluster. The output then comes from the ECU to the speedometer and can only be a square wave. Im wondering what I can do to resolve this (Ie: some kind of square wave to sin wave convertor) and how to wire it into the cluster (ie: what can I omit from the factory inputs to the speedo - do I still need pin 28 and 24?)

The original inputs/outputs to the factory speedometer (without heads up display):

- ground - pin 28,

- Switched voltage - pin 24,

- signal from VR sensor - pin 6,

- Signal ground on VR sensor - pin 12,

- square wave signal to ECU - pin 7

Someone give me some advice! I heard it is possible to use a RC circuit to convert square to sine but it would only work for 1 frequency, not the whole range.. not sure what the solution is to that.

Factory speedo wiring picture below, hope its clear. Thanks in advance!

Attached Files

Might just be easier to fit a VR sensor compatible with the Speedometer.

I have successfully driven a skyline speedo using a simple decoupling circuit to create an AC like signal that will cross zero from a squarewave. This circuit will be affected by other factors in the circuit such as the pull-up on the output and impedance of the speedo etc (note our ECU outputs a low side drive square wave pulled up to 12V with 1.5kohm).

https://forums.linkecu.com/topic/11516-g4-speedo/?do=findComment&comment=74473

Interesting, thanks for the responses. So a follow-up question:

The original VSS circuit shows that both the wires from the 2-wire VR VSS go to the speedometer.

The output signal from the ECU I assume would need to be grounded to chassis if it is a 12V output as you say?

If I manage to convert the output signal from the ECU to an AC sine wave, I would supply the speedo with this signal, and ground the other wire?

Thanks in advance! I'm sure this is an elementary question but I'm finding difficultly finding a clear answer.

Measure both sensor wires with an ohmmeter connected to ground, I think you will find one of the wires has continuity to ground.