about pin 46 in EEC-4 (...and octane adjust, and more)

[opexo]

Pin 46 in eec-4 in many places is mentioned as "common sensor ground"

In many schematics it is shown connected to the 'other' ends of the ECT, IAT, TPS, Camshaft and HEGO sensors.

What really is the difference with the 'regular' ground aka the battery negative?

 

In connection with the above, on my 1993 1.6 zetec Escort i remember the octane plug used to be shorted to ground, on later years escorts and mondeos it's shown to be connected to the "common sensor ground". So what's the difference really? The octane pin needs only to "know" if its 'opened' or 'closed' as in logical 1 or 0, it doesn't require particular voltage, so ground is ground..

 

I had some issues with grounding in the past i pulled one beautiful thick black wire from the battery negative to pins 16, 20, (30?), 40, 60 and solved it, but i'm about to connect it to 46 so i want to know again does it have at all any difference.

 

 

p.s. it's all part from a plan to stabilize all electrics in the car especially everything connected with engine operation. That will be with diodes and condensators and other techniques so i need to know whats what in the ecu and around it.

[Craig855S]

If the wire in pin 46 has continuity to earth under all circumstances (isn't switched after the point where it goes in the ECU) then it does not matter wether the pin is jabbed in pin 46 or earthed through a stud in the chassis or any other part of the car that has continuity to the battery negative. I am confused why you want to "stabalise the electrics" though. Earth is earth, and its not unstable unless the wiring is damaged, and one way to help it get damaged is to mess with it. If you think you can use better cables and terminations and route wires in a better way than ford did to prevent "damage" then crack on but i really dont see the point Edited August 8, 2013 by Craig855S

[Stu]

First of all, your objective is going to lead to failure and doom and kittens will explode all over the planet.

 

There are different grounds in a car and there is an expected voltage differential between them. Sensor ground is not chassis ground. There is a reason it's there, it's a reference point. Chassis ground varies depending on where you pick it up from. Bad, bad, to mess around with it. You'll end up with problems. Leave it how it was designed. If something is damaged, replace it as-is, don't try and think you can improve it.

[SteveB]

First of all, your objective is going to lead to failure and doom and kittens will explode all over the planet.

 

There are different grounds in a car and there is an expected voltage differential between them. Sensor ground is not chassis ground. There is a reason it's there, it's a reference point. Chassis ground varies depending on where you pick it up from. Bad, bad, to mess around with it. You'll end up with problems. Leave it how it was designed. If something is damaged, replace it as-is, don't try and think you can improve it.

 

Correct of course! The point you (not Stu!) have missed is electrical resistance. It might only be a few milliohms, but when you stick a current through it you get a voltage drop. Connect a sensor earth to the wrong point and the voltage drop gets added to your signal = exploding kittens - probably puppies and rabbits are done for as well.

[opexo]

You made my day lol

Some say... putting things in the fridge protects them from the initial blast wave