Apex

Appreciation for this forum as I've re-built most of the bosch connectors and hoods on the engine harness. An adventure in crimping. 🤣

But I'm curious why the gauge sensor doesn't have a bosch connector, instead is two uninsulated spade terminals?

Over the years as the wire insulation became hard and inflexible, it created a stress point and some of the wire strands have weakened and broken from repeated movement. I'm refreshing these two connectors and wire but wondering why it is this way in the first place?


Copper water temp spade terminals



DME and gauge water sensors

931guru

Because Porsche designed it that way.

And they probably designed it that way to use parts that were already available and cheap.

harveyf

You don't mention the year your car was made but generally speaking, there are two water temp sensors. One does have a blue Bosch Junior Amp connector. The wiring to this one goes to the ECU and is input to fueling and timing decisions by the ECU. The one with the spade connector feeds the gauge on your dash. I don't know that they were being cheap. I would say that many connectors for sensors leading up to the 80's used spade connectors. Using the Bosch connector for the inputs to the (then state of the art) ECU system was most likely mandated by Bosch to reduce sensor uncertainty. My experience is that instrumentation guys (from my nuclear background) will tie themselves in knots trying to determine analytically what the uncertainty is in any sensor circuit, especially one that is an input to an active control system. And yes, the Bosch sensors would have been much more expensive, relatively, to the one with the spade connectors. Even at Porsche, they knew that pennies added up to real money over the production life of a car.

Apex

Economy and path of least resistance will mostly win over consistency every time. 😁 My car's a '92 coupe.

Harvey BTW I just took a peek at your blog—super-impressive. I'll return there to read up on your 944 rebuild.