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View Full Version : Knock sensor only 3.3 volts?


casman86
06-15-2012, 11:41 PM
'm throwing a code 34 (knock sensor) on my 95 ka-t and have been testing the wiring to try to figure out my problem. I read somewhere that the signal going to the knock sensor with it unplugged should be 5v. I got 3.3v from the connector to the subharness, so I de-pinned the wire at the ecu plug to rule out the wiring. Same reading, 3.3 volts straight out of the ecu.
This is on a JWT ecu, so I swapped it out for my stock ecu and it also read 3.3v!
I've been scouring the internet and have found others with the same issue. This makes me wonder if it is actually supposed to be 5v or if that's bad info. The fsm only lists the voltage with a knock sensor connected (2-3v).

If it is supposed to be 5 volts, what could possibly be making it put out 3.3 on multiple ecus?? This is blowing my mind.

casman86
06-19-2012, 02:41 PM
Alright, so I'm going to say that 3.3 volts may be normal. I did a knock sensor bypass with resistors totaling 560ohms to mimic the factory sensor and it throws no code 34 now. So the 5v thing may be bad info.

nismolvr
06-21-2012, 08:20 PM
http://zilvia.net/f/engine-tech/62607-sr20det-faq-5.html#post3555484

kawasa
06-27-2012, 08:30 PM
'm throwing a code 34 (knock sensor (http://www.car-stuff.com/knocksensor.htm)) on my 95 ka-t and have been testing the wiring to try to figure out my problem. I read somewhere that the signal going to the knock sensor with it unplugged should be 5v. I got 3.3v from the connector to the subharness, so I de-pinned the wire at the ecu plug to rule out the wiring. Same reading, 3.3 volts straight out of the ecu.
This is on a JWT ecu, so I swapped it out for my stock ecu and it also read 3.3v!
I've been scouring the internet and have found others with the same issue. This makes me wonder if it is actually supposed to be 5v or if that's bad info. The fsm only lists the voltage with a knock sensor connected (2-3v).

If it is supposed to be 5 volts, what could possibly be making it put out 3.3 on multiple ecus?? This is blowing my mind.

As far as I know is that it is 2.5 volts when the car is running and 5 volts when the ignition is on.

Either way, it is 3.3 volts whether the car is running or not.