Correct, as the +5V TPS and +5V AUX lines go directly to the connector to the EMS. From the connector these two lines directly power sensors on the engine.TheRevva wrote: The way I 'read' the schematic, it will protect the +5vSwitched from over voltage (and, as has been mentioned, the 5v6 Zener looks somewhat superfluous now).
However, it will NOT protect the +5vTPS and +5vAux lines at all.
You do not want any kind of crowbar in this situation as current would only be limited by external fuses.
The internal 5V is protected by this circuit and if someone connects 12V to those external lines the polyfuses protect the EMS from damage.
If external sensors break from 12V...that is out of the scope of the EMS.
Both digital and analog inputs have their own OVPTheRevva wrote: Thus, if some IDIOT (like me) somehow connected +battery to the +5vTPS line, this line WOULD shoot up to battery (and therefore the actual TPS wiper input would jump up accordingly possibly causing the TPS analog input protection to activate.
(The TPS would still function, but it would be 'read' as full scale from about 5/12 of its wiper travel through to WOT)
I'm not 100% certain what is connected on the +5vAux line. My 'assumption' is that it's for external Hall Effect / Opto sensors.
As far as I'm aware, the majority of such sensors will quite happily survive on full battery voltage and for those that cannot, it's NOT the fault of the EMS!!!
Furthermore, I understand that most such sensors use an open collector type output and as such they would not affect the corresponding EMS input.
However, there _are_ some sensors with internal pull ups that might feed +battery back into the unit (thereby activating the OVP on the associated input)