I like to know where the actual wires from the ECU for pin 1 and 19 for grounding the ECU are attached to the chassis. When measuring these two points towards the chassis of the car I get a 0.3-0.4Volts differents so the earth connections are not perfect.

Who can tell me where in the car these wires from the harness are attached? It's a Ford Sierra Cosworth 4x4.

 

They are earthed to the plenum. 2 brown wires at the throttle hanger.

 

Thanks Stu for this quick answer!

 

I thought that was for a 2wd loom STU?

All 4x4 saph looms i've had the earth is attached via a bolt that fixes the 2 parts of the plenum chamber together but not at the throttle cable hanger its further back toward the bulk head behind the throttle body and to the back & bottom of the plenum (1 bolt back & bottom from the end of plenum if my memory serves me right)

I've always personally run an extra wire from the plenum to the negative side of the battery

 

Apologies, I just assumed 2wd vehicle and didnt read it properly.


Matt is right on all 4wd variants its on the 2nd to lower last rear plenum bolt.

 

you should never earth these to the battery or connect a spur to the battery from them.
they are earthed in that position to avoid signal noise, which is why ford never earhed them to the battery!

 

i don't earth it direct to the same point as the loom earth i take it from 1 of the top plenum bolt holes