Right, the first figure of 14v is, as you probably know, alternator output voltage which is totally normal - so must be between 13.5v - 14.5v. Sometimes it can be 14.7v when cold but that's ok too, it will settle down to around 14.5 or below once warmed up.
The second voltage of 3.5v that the Yank got.....Do you know if this was with the TCV plugged in OR unplugged?
If it was unplugged, and your checking the voltage at the lume, then that is voltage from the ECM.
You have to remember that a TCV is an actuator.
Sensor = input to a system (ECU) meaning it supplies changing voltage to the ECU (or in our case ECM)
Actuator = output from a system (ECU) meaning it receives voltage from the ECU (or ECM)
So, the TCV should be getting what we call "12's and 5's" ie 12v and 5v. Obviously that's not an exact science, as if you were only getting
12v and 5v (across two different pins) then that would tell you the engine is switched off, so you'd be seeing battery voltage. Everthing powered by the vehicle recieves the same Battrey voltage 12v when switched off and
charging voltage ie 14v when running.
So, the TCV should have 14v (charging/Battery voltage) on one pin if the engine is running and a voltage from the ECM...ie 3.5v (If that is correct for the ECM at idle) on the other!
(If I've got that completely wrong, then can someone please pipe up and put me straight
, as it's 7am and I've only just woken up!)
If I remember later, I'll check my car for you when I get home from work.
I will check both with the engine switched off and running
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