ozziesironmanoffroad

im having this problem now too.... damned code 52! im getting such horrible gas mileage! have you fixed your issue yet??

94blueyoter

I just put a new motor in my 94 pickup (22re) i am having the same problem. Got a code 52, i disconnected my knock senser pigtail, so i know it not the knock sensor ( right??). i read how to test for the short and the open in sb5walker's post. so if there is no short/open then it leaves you with the ks pigtail, and the ecu (?) so is there anyway to test the pigtail first before testing the wire??

i have killed a half tank in two days ( ~40 miles!) normally a week worth of gas!

and extreme loss of power, feels like im pullin a trailer

BT

Pretty sure that if you disconnected the pigtail, you now have an open which will produce code 52. For mine, I just had to clean and scrape the contacts. It took a few tries, but it eventually made good contact and the code went away. Never came back after that. Maybe I was lucky...

shaeff

Correct. Code 52 is registered when there is NO signal reaching the ECU. The knock sensor is a piezoelectric element that outputs a signal to the ECU. No signal = code 52.

94blueyoter

i did the same thing, sprayed the pigtail with some brake cleaner and put it back on....no code. i drove the rest of yesterday (12-17-2010) no check engine light. THEN i was doing some donuts, in the snow, at about 1400rpms and out of the blue it comes back up. turned the truck off, started it back up no code. drove home no code. went to whip it around a corner, revd to 1800 dumped the clutch and it came back on. so i restarted the truck and it stayed off the rest of the night. this morning i hopped in it headeed to school and it came back on less than a mile down the road....im clueless i thought i had it fixed last night. its not the sensor cus when the light was on i unhooked the sensor and the light stayed on....?

scope103

I'm probably repeating what other's have said ...

The knock sensor is a generator of alternating current. It is not a switch to ground or a resistance. You cannot check it with an ohmmeter. When the engine is running it is generating a small signal, until the engine starts knocking, when it generates a larger signal.

So if the engine is running and there is NO signal (like you unhooked the sensor ...), the ECU knows that something is wrong, and it throws the code. Thats all there is to it. You can get no signal (and therefore a code) from unhooking the sensor, shorting out the wire somewhere from the sensor to the ECU, or by having a completely dead sensor.

The sensor is inherently robust, but on the other hand, the pigtail sits in "wire hell." So the most likely cause of a code should be the pigtail (either the wire is broken giving an open, or the wire is contacting the shield (or other metal) shorting it to ground).

You can directly test the knock sensor with an oscilloscope, but you probably don't have that. Someone on this forum (I can't find the post) removed the knock sensor, held it in a vise, vibrated it with a stalled drill-driver, and measured the output with an ac millivoltmeter (clever!) The the knock sensor is "tuned" to a certain frequency, so that test is a little hit-and-miss.

By the way, I DON'T KNOW what resistance you would get if you measured the input connector on the ecu. If it is measuring output current you would probably see a short to ground, if it is measuring output voltage you might see an open. The point is that you cannot test the entire length of wire from the knock sensor to the ECU with the wire connected at the ECU end. You need to disconnect the connector at the ECU to do an end-to-end test of the wire (which is probably a good thing to do.)

Good luck!

94blueyoter

ok i havent had any knock sensor problems in a long time. i took the knock sensor out and scrapped the connector of good and cleaned with brake cleaner, as well as the pigtail. i have been driven for a while and nothing happens.
BUT...i went to the next town over, the speed limit one on road was 55mph, and the knock sensor code comes up. shut the truck off, start it back up (while rolling). continue driving and the code comes back up. ONLY when i reach 55mph or higher its comes on. What is this all about????

REALLY need help guys!

Hadmatt54

There is one scenario that no one has mentioned. Your knock sensor wire is a multistrand conductor, if it is broken under the insulation there may be a strand or two still touching that will give you a good continuity test, but not enough strands still intact to allow current flow. To check for a broken wire connect to each end of the wire to establish continuity, then check the entire length of the wire moving and twisting it to see if you lose continuity.
As far as your knock sensor coming on at 55, it almost seems like you have a speed related noise or vibration that is the same frequency as a ping in the engine that the knock sensor is picking up.

94blueyoter

QUOTE]As far as your knock sensor coming on at 55, it almost seems like you have a speed related noise or vibration that is the same frequency as a ping in the engine that the knock sensor is picking up. [/QUOTE]

i have some Rocker Arm noise. i dont know if they are worn out or what. but when i rebuild the engine (3rd time now) i readjusted them because of the new short block. i have always had noise from my rocker arms but it has never before cause any codes to go off.

A buddy of mine told me that it may be pullin the wire so that it loses its connection, when im at 55mph, because of the load on the engine causing it to shift a little bit. but the only way i can think to simulate that is to put the truck on a dino and run it to 55mph and check the wire...any advice??

Lumpy

I'd check the wiring on the sensor. I had similar issues and it turned out being a bad splice from the P/O.

shallowrunner

Uh..... someone please correct me if I am wrong...but are you trying to say that you get a code 52 because you are "losing" connection to you knock sensor?????

My understanding (again I could be wrong) but I thought you only got the code if the engine DETECTED a knock. If you are running at higher RPMs... then you may indeed have a slight knock that you ecu is picking up. I had a code 52 (i think that was the code) on my 3.0 and it was for a knock sensor. At first I thought it was not working. So I inserted a pin into the wire that feeds the ECU. Attached my multimeter to it and one to ground. Took a hammer and rapped the block once. I saw a spike in voltage. That told me that the knock sensor was indeed working. So as it turns out... I had a knock issue once I passed 2000 RPMs. Ended up being that the guy who replace my head did not shim the valves properly and it generated a knock at higher RPMs.

I tried finding an error cod 52 for the 22re engine but just can seem to find that. Are you absolutely sure that it means you are grounded or lost connection...... or does it really mean that you are getting a code 52 because you actually have a KNOCK in your engine at higher RPMs.

I find it hard to believe that your timing is on... when you distributor is pegged to one end of its travel. What timing did you get with the "T"connector jumped and with it not jumped? Should be 12 without and 5 with.

Shallowrunner

shaeff

Correct. Code 52 happens when the ECU loses the signal from the knock sensor.

Your understanding is incorrect. Code 52 has nothing to do with actual knocking. It's an electrical problem ONLY.