shadowrider13

That is the knock harness connects I need the one off the main harness that connects to knock harness

shaeff

Oh, I see. Even still, your best bet is to either A) see if it's available from the dealer, or B) find someone parting out a truck and get them to clip a length of wire including that connector off and ship it to you for somewhere around $10 or less.

I don't know the P/N for that clip offhand, nor can I find it while using this computer.

Ztraub

The reason this is hard to diagnose is that the KNK signal is not a discreet signal (+ or - 5 or 12V) , Not a contact or resistor. It's a signal that amplitude increases as knocking occurs. Relatively small signal compared to other voltages in car electronics. Signal attenuation and rf interferance can degrade signal. In normal operation you should see a signal on an oscilliscope with a frequency of 7.1khz. with an amplitude about 400millivolts. Knocking apperas to approx triple that amplitude. I wish iknew how the ECU senses the signal my guess is some sort of slope detecting circuit for frequency, no idea about how it measures amplitude. There are a lot of ways. The simplest would charge capacitive resistave circuit and adjust timing till average stored value insured no knocking. Smaller amplitude = smaller ave charge. It could also be a comparative op amp that send a True to cpu when amplitude reaches preset value. Either way continuity is 1st thing to check. No open to ecu, no short to ground, But you have to consider shielding and degraded capacitance values that will attenuate signal. In the signal wire inbetween the signal conductor and the shield is insulation/dielectric that go bad with age the thin spots and kinks cause signal attenuation. TRY A NEW WIRE. Trust me, 20 years RF Technmician/Electrical Engineer.

dszx13

New to the site an toyota a all together bought my first one 1990 extended cab 3.0 5 spd stock for now. Checked the code an 25 an 52 came up it was a fresh rebuilt motor with head work. After the truck warms up at idle Rpms jump up an go back down constantly push the clutch in its fine any idea why it does that I kno knock sensor pig tail an a new wire is what I need to change

dszx13

Any input??

runs-on-4

iTrader: (1)

who can explain this, ive been dealing with my code 52 for awhile now, one day i was tinkering around and unplugged #1 and #2 plugs and started up the truck reved a few times and let it idel for a few mintues the code went away when i pluged the plugs back in and started it again, lasted about 150 miles and came back did the same thing had the same results ive been doiung this for about 2000 miles now doesnt always go away the first time have to repeat 2 or 3 times at most.. but it works and is better than pulling the engine apart to replace

dszx13

.....

rc14

iTrader: (1)

I have never encountered a code 52 problem I haven't been able to fix. Ever. I've been doing it for about seven years, and have cured the problem for well over one hundred people. I'm not sure what you're doing wrong here.

Ok i have a code 52 that i need help with, I have checked the pig tail and its fine and the KS looks new as the PO said it was but it all back together along with new timing belt water pump and pulleys tensioner and so on. Still code 52 got another used KS and pig tail from a friend and installed it externaly and still code 52. next step run coax wire from ECM to KS Will i need to solder the coax wire to the wire coming from the ECM ?
Thanks
Roger

rc14

iTrader: (1)

Last Post was for Shaeff.

shaeff

Hey Roger,

You've got a few options here. You can cut the knock sensor wire a few inches from the ECU connector and solder your coax in there. (if you get stranded coax you can crimp it, but use heat shrink over your crimp to prevent corrosion). If using solid core wire then do not crimp it.

Or you can de-pin the connector, and solder the coax directly to the pin, then just pop it back in place. (this is the method I use)

On the knock sensor connector side, I do the same, I de-pin the plug, solder the coax directly to the connector, and pop it back in place. Don't forget to put the rubber plug on the wire before you solder the pin on, otherwise you risk stressing your solder joint when trying to force the pin through the rubber.

Make sure you ground the shielding wire at the ECU side to a good ground. Also, I never use aftermarket knock sensors, only OEM Toyota sensors. I have had issues with the aftermarket ones on more than one occasion so I stay away from them now.

rc14

iTrader: (1)

OK I used coax cable from ECM to the KS and i did solder, at first i de-pined the connector but was afraid i would brake the connector so i put it back and cut the wire about 4 inches from the ECM and soldered. but i did not ground the shielding i need to go back and try that.
Thanks for all your help this is getting old.

rc14

iTrader: (1)

Shaeff I did like you said and grounded the shielding wire on the coax cable and found a better place to mount the KS cleared codes and started it and could get it to give a code in the garage, will drive it tomorrow.

Thanks
Again.

rc14

iTrader: (1)

ok I got the son to drive it today and he said it is doing the samething going in to limp mode but this time no engine light. any ideas.

rasdavid5446

tried changing the knock sensor checked wires no good but then i tried blowing on the tube to pcv valve and 93 gas and bam check engine light off. so it may have nothing to do with knock sensor circuit but it works

h_louviere

1992 pickup 4x4 3.0 manual. Ok guys I need some help. Damn code 52. Here's what's going on. Once truck is started no cel. With truck in neutral I can ease into the throttle and bring it up to 4k+ rpm and no cel. But if I were to pat the pedal and bring the rpm up quickly cel comes on under 2k rpm. And it's code 52. I also unplugged the sensor and reved it slowly and same result, no cel. ALso when I drive it, I can take it real easy trying to increase rpm slowly but cel comes on around 20mph. And never get over 2500rpm. I've relocated sensor to engine hook until I figure this out. New sensor and pigtail. I have two ecu's and the cel comes on the same regardless of which one is in. Need help. If code 52 means the sensor isn't detected why can I rev it slowly until redline with no code? I'm stumped on this one!!

scope103

All Answers are found in The Good Book:

"With engine speed between 1,600 rpm – 5,200 rpm, signal from knock sensor is not input to ECM for 6 revolution. (KNK)"

So just like it says, you have to get it up into 1600-5200rpm to trigger the CEL. The ECU is not hearing from the knock sensor.

Since you've already replaced the pigtail (good), the sensor and ECU (probably not necessary), that leaves the wiring from the pigtail to the ECU. It's shielded to protect it from the EMI in the engine bay, so if the wire is damaged it may fail to get the signal where it wants to go. First, ohm it out. Make sure the shield is continuous to ground (and don't go nuts; the shield is connected to ground at the ECU only; don't try to ground it to the block). If that's all good, ease it out of the harness and inspect for physical damage. Many have successfully replaced it with Parts Store shielded cable, like microphone cable.

And if you haven't already figured it out yet, "relocating" the knock sensor to the engine hook will pretty much assure you get code 52, no matter what the wiring is doing.

h_louviere

[QUOTE=scope103;52252649]All Answers are found in The Good Book:

"With engine speed between 1,600 rpm – 5,200 rpm, signal from knock sensor is not input to ECM for 6 revolution. (KNK)"

So just like it says, you have to get it up into 1600-5200rpm to trigger the CEL. The ECU is not hearing from the knock sensor.

Since you've already replaced the pigtail (good), the sensor and ECU (probably not necessary), that leaves the wiring from the pigtail to the ECU. It's shielded to protect it from the EMI in the engine bay, so if the wire is damaged it may fail to get the signal where it wants to go. First, ohm it out. Make sure the shield is continuous to ground (and don't go nuts; the shield is connected to ground at the ECU only; don't try to ground it to the block). If that's all good, ease it out of the harness and inspect for physical damage. Many have successfully replaced it with Parts Store shielded cable, like microphone cable.

And if you haven't already figured it out yet, "relocating" the knock sensor to the engine hook will pretty much assure you get code 52, no matter what the wiring

. I can get it up to well above 1600 with truck in neutral if I go slowly. And hold it there for a while. And no cel. But if I were to rev it quick the code comes on prolly around 1600-1800. When I rev it quick it almost feels like it chokes for a split second then the light comes on.

jbtvt

Would the shielding cable in this application be solely for the purpose of providing a reference voltage (if EMI induced voltage is detected in shielding cable the ECU adjusts the anticipated reading for the signal wire accordingly), or is it actually supposed to absorb any errant EMI?

^ Regards to above, two possibilities come to mind. One is that you have a break in the wiring which lies right next to grounded metal, when you rev slowly the engine doesn't vibrate enough to jostle the wire against ground/short, but when you stomp it, it bucks and shorts out. Another might be that your shielding wire is faulty and a quick acceleration causes a brief spike in alternator output or some other source of EMI under the hood. However, while it seems likely this could cause the ECU to correct for non-existent "ping", I'm not sure it would actually cause a CEL, unless the voltage spike was strong enough and in the right wave direction to completely cancel out the knock sensor signal.

IF EMI can trigger CEL it would also make sense that any instances where people have simply moved the knock sensor to the engine hook (terrible idea for long term use!) WITHOUT installing any new components and seen the code 52 go away may be related to weaker EMI in that location as opposed to stock. They could also have a smal break in the insulation and moving the wire was enough to get it away from the area it was shorting out to. Of course, if you install a new sensor and move it to the hook it's more likely you just had a bad sensor.

Incorrect. The definition of a closed circuit is one in which electricity can flow from the hot source to ground without interference (IE a light switch in the "off" position). Every electrical outlet in your house is a closed circuit when connected to an active appliance, the fact that all outlets ground to a common bar in your breaker box doesn't affect that.

h_louviere

I guess that could be a possibility. But it seems like while driving and slowly increasing speed and Rpms the cel shouldn't come on.

scope103

I'm not sure what you're getting at here, but there is an important point buried in that discussion. The shield in the wire to the knock sensor is connected to ground at the ECU and nowhere else. This is (probably) to prevent what audio guys call "ground loops." That's why the pigtail connector has two pins at the harness end (to carry the shield through), but only one at the sensor end (no connection to shield there). As long as you use factory wires, everything is taken care of. But if you play Dr. Frankenstein and start making up your own harness, you need to keep this in mind.

So asking whether it is a "closed circuit" is just missing the point.

Also, EMI doesn't trigger code 52, it obscures the knock sensor signal. The code means "I can't hear anything from the knock sensor," whether from a dead sensor, broken wire, or a non-working shield which lets in so much noise the ECU can't hear the signal.