fredtheturd

Hey guys! I hate to kick this dead horse, but I'm at a road block. I replaced my knock sensor & wire summer of '06. Code 52 came up about 2 days after I replaced it. I've left the battery cable off overnight a few times & pulled the EFI fuse a few times as well. It took me all July 4th weekend to do the job by myself in my driveway & I'd sure hate to have to shell out the cash & do the job again for nothing.

Could it be the wire to the ECU? Maybe the ECU? How can I check these?

Appreciate the help!

OSU4Runner

Whats code 52 for?

fredtheturd

Knock Sensor Signal--open Or Short In Knock Sensor Signal
--knock Sensor/circuit

Ecu

Emms4runner

Common problem this one..

fredtheturd

Yes! Exactly! It runs great but as soon as that light comes on, it runs like a sick dog. I gotta get this figured out somehow.

InternetRoadkill

The ECU is going into limp mode when the light is on. More than likely, it's going to retard the timing a bunch and run the mixture rich.

Did you try cleaning the connector? Maybe it's corroded or full of crud. Knock sensors are pretty reliable. There's no moving parts in them.

Guardian_Saint

Maybe the wire to the ECU or plug is bad? The plug that connect to the KS wire.

slater442w30

you need to backprobe the sensor with a lab scope to make sure its actually working, then make sure there isnt any excess pinging or noises in your engine sending the knock sensor into overload causing it to go into limp mode, my truck was throwing knock sensor codes when it was still a 3.slow and I started running premium gas only, no more codes but no better mileage.

Knock sensors are the devil

DilutedImage

Unplug the wire that connects the sensor to the ECU at both ends, and then use a multimeter (or volt meter) to test the wire for a ground. You could test for resistance (ohms) by connecting one end of the meter to the wire you're testing, and the other end to any suitable ground (frame, block, etc...). Or, you can test for voltage by connecting one end of the meter to the wire, and the other to any +12v source (such as the battery). If either of these tests produce ANY result, then the wire is grounded out somewhere. If that's the case, then it's time to trace that wire all the way back to the ECU, looking for any sort of damage.

Of course, this is assuming that there is actually something wrong with the circuit, rather than something actually causing an engine knock.

Ganoid

You may want to try a few extra engine grounds as the knock sensor signal is pretty low voltage and can easily be lost in a bad ground situation. You can never have to many engine grounds.

timebandit

Code 52 means the ECU cannot see the sensor. Or it is loose. 33 ft.lbs IIRC. I find a lot of them loose. These are the only conditions that will turn the light on, an open in the knock sensor circuit, a bad knock sensor or bad ECU.

Emms4runner

Toyota cant get anything right!

timebandit

Most knock sensors send a base no knock reference signal to the ECU. I am assuming that you have traced all the ECU grounds? And that KS circuit?
Check that sensor to see if it is shorted to it's case. RFI from any other electrial stuff nearby might cause a problem. You may also want to check the spark plug wires. High secondary resistance can cause high RFI levels, which can trigger false codes.

Emms4runner

Toyota shoulf fix this under warrenty.

Ganoid

yup grounds = earths

If you want to get an idea of how much voltage loss you are seeing between your engine and battery you can use a voltmeter. Set the voltmeter to a lower setting (under 20v) then hold one end to the negative B terminal and start touching other grounded things with the other lead. Every item you touch with the other lead it should read you the voltage difference. One common one is to touch the -B terminal and the alternator casing to see what kind of loss is present. In a perfect world your -B terminal combined with any other grounded part on your truck would yield 0.00 volts. You may need to set your meter to single digit voltage settings to see the differences but I assure you they are there. Another interesting thing to test is to pull your light socket off your headlight and do the same trick but testing the -B and the + light terminal. Then compare those numbers to the +B and -B measured at the battery. I have seen cars that lose 2+ volts in the wiring harness before the power reaches the headlights.