SP1 speed sensor

[alunwill]

I've read on here somewhere that the SP1 sensor which drives the instrument cluster is a 20 pulse hall effect.

Is that correct or is it a 4 pulse system. I've been trying to get an aftermarket speedo to operate and it hardly moves whilst I'm testing it on axle stands.

Waveform looks nice and clean, 12v square wave but just doesn't drive the unit unless I programme it to operate as a 4 pulse system.


Thanks



al

 

[gloverman]

They can be 20 pulse or 4 pulse depending on the different models. If it works on 4 use that. Or seeing you can monitor the signal test it. Mark the driveshaft , put the box in neutral and give it a turn.

 

[alunwill]

well, I checked the pulses per rev of prop-shaft today.

I've got a 2 pulse system when measuring SP1. That is 2 transitions from high to low. Not sure if the 4 pulse means 4 transitions (leading and trailing edge) but mine is definitely a 2 pulse with 4 edges!


changed my speedo to reflect 2 pulse, followed my day car down the road at 20mph and speedo reads fine.


So, is it 20,4 or 2 pulses verses edge transitions that this system works off!


al

 

[gloverman]

which model sensor are you using?

 

[alunwill]

Don't know the sensor model, it was standard fit in a 93 reg car. Fully in tact and running well before I took the engine out for transplant