Does anyone know what the single wire sensor going into the back of power steering pump is for? The reason I ask is that I recently purchased a second hand pump and this sensor is not there. Will using this pump without a sensor be a problem? I thought about putting the old sensor into the new pump but the hole is different and will not accept the sensor. Also there is no communication hole between the pump reservoir and the hole for the sensor on the new pump so presumably it is not designed to have a sensor there?
Any thoughts gratefully received!

 

I believe this is the Power steering oil pressure switch, this is on a blobeye so I can't speak for other models.

 

Thanks for that. Should the second hand one I bought have a switch in? Does anyone know if there is a variant that does without it? The pump has come from a 98 UK turbo I think. I have a suspicion that I have been sold the pump without an integral part.