Looking for some advice please, Are the wires from the CTS to ECU shielded ?
I don’t recall mine being that, and it’s not indicated on the elec illustration.
It’s a check on resistance anyway, not a voltage - which is more often shielded (but not always).
Not shielded on mine (‘88). The circuit is actually a voltage divider; 5V from ECM fed through CTS and back to a termination resistance in the ECM.
I had to parallel a resistor with the CTS on mine to get the voltage vs coolant temperature correct, as my ECM termination is off. Easier than a new ECM. I think there are voltage vs temp listed in the V12 Focus manual.
Thanks… Much better way of saying it. To clarify, I meant that the shielded wires to the ECU are often used when an external voltage is SUPPLIED to the ECU from the sensor, as is generated by the O2 sensors, Amplifier, or VR pickup, vs when a voltage is applied FROM the ECU through something with variable resistance.
More to do with whether it is an a/c signal and frequency it operates at; noise/interference from ignition, alternator, or associated circuits can be induced in an unshielded circuit and cause false inputs. CTS is a slow changing DC voltage, relatively speaking.
Thanks, Paul and Robert re. wiring to ECU, your help is most appreciated.