Tweet
late to this ****, and know very little about these things.
but should the Voltage to the knock sensor be 5 volts, not 3?
but should the Voltage to the knock sensor be 5 volts, not 3?
-
-
Best to keep it all in your thread.
But I would think about measuring the 5 volts while disconnection different sensors that it feeds to weed out some of them dragging the voltage down.
seem I read about some water pressure sensor or maybe something else leaking and sending water into the wiring screwing things up.
but just about any of them could ground out and suck the voltage down.
just a thought from a non expert on those big motorsComment
-
Good evening and again, thank you all for your inputs. I am under the impression that the knock sensor may not be receiving the correct voltage. I have 3.16v coming from the ECM when the sensor is disconnected and 1.92v when it is connected. I would like to rule out all other sensors possibly being shorted causing a voltage drop. Ive attached a shot of the manual showing that theres no referenced voltage for the KS. all input is greatly appreciated.Comment
-
ok so I have no idea why those picture are so damn small. I just want to take my kids fishing and know their safe.... FMLComment
-
Well I may have not helped at all, and lead you down the wrong path
someone will have to chime in on if the Knock sensor is suppose to have 5 volts to it.
If manual says it does not that is probably correctComment
-
Where is rodnut when he is needed?
I have generic Yamaha data that indicates a 5 volt output to a knock sensor. But it is not specific to the F250. And all Yams are known to not function in the same manner.
Again, Yamaha data is severely deficient when it comes to trouble shooting. Current data is still crap IMO. It looks good but only because it is better than it once was. Maybe by the next century they will get it right. But I doubt it.Comment
-
Can you find a fellow boater that has an F250 that will let you check the output voltage from his ECU for the knock sensor?Originally posted by Nourse1168 View PostComment
-
-
is this a 3.3 250 or a 4.2L 250. best I recall,and there isn't much published, that should be a 5v signal.
the 3.3 requires cyl head removal to access it, the 4.2 I can do without removing the heads.
Comment
-
Rodbolt, this is a 3.3 350. You have to pull both heads in order to remove the KS.Comment
-
3.3 f250 i mean. not a 350.Comment
-
Ive grounded a new knock sensor to the block and I still get 3.16 volts. When I test drove the boat a few years ago before purchase the rectifier regulator got so hot it melted it mounts. Maybe the ecm was damaged when that happened.Comment
-
Comment
-
can you measure the 5 volt output to all of the other sensors to see if they also have low voltage or maybe just some others have the same 5 volt output.
if you find more than just the KS low then disconnect them one by one to see if the voltage comes back up to 5.
all of this depends on if you find more that read low and that the KS is suppose to have 5VComment
-
carefully look at the diagram.
you note a piezioelectric crystal shunted by a resistor.
there is a (voltmeter) inside the ECU that is measuring the DC voltage dropped by the resistor,when a knock is detected the piezio device sends an A/C signal riding on the reference.
it is always possible a different sensor is loading down the 5v ref.
they wont show us a circuit diagram inside the ECU.
I use a small MAR-PAPER-CL-IP to back probe the connectors.Comment
Comment