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Discussion Starter #1
I have just over 140000 miles on my 1st gen and have the knock sensor code. I have read through many of the posts about it here and thought the general consensus is that the sensors themselves rarely go bad, it's the harness that's the culprit. I am thinking of just replacing the harness and while I'm in there, change the by pass hose and the spark plugs. I bought the vehicle with 106000 miles, so as far as I know these may be the original spark plugs. Maybe they are worn and causing a knock due to poor spark? I have also read that irregularly worn tires could make the sensors go off? That seems unlikely to me, but mine are worn and I was going to be replacing them soon. So has anyone just replaced the harness with success? Most say this is a difficult job, I usually work on everything myself or with a mechanic buddy and from watching a few videos and looking at the vehicle it really doesn't seem like that big of a nightmare to do. Not that I want to be overconfident and then get my butt kicked! It's going to be a couple weeks before I can get the parts and time to do this,thankfully I have a truck to drive in the meantime, plus the engine light comes on after about 5 miles of driving after I reset it!
 

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I believe this is a sensor code and not an indicator of real knock
I would Check the shielding continuity and disconnect/ reconnect the harness at the connector near the transmission and clean the engine and ECU grounds and battery cables at both ends. If you have access to a lab scope there is a test in the FSM to check the output.
if you actually have pinging and drivability issues it may be from excessive oil consumption through the PCV system due to sludge in the valve cover baffle. Several threads on that. If you decide to change the knock sensors you might want to address that issue too. You may want to do combustion chamber cleaning
 

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In my experience, bad or worn spark plugs will cause a miss, not a knock. Like C R says, carbon build up can cause a knock though. You would probably have noticed some oil consumption by now if that is the case.
 

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2003 Highlander
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scrambledtracker
My 2003 HL is experiencing the same problem. The fix is (not that) simple. I've even purchased the parts and e-torx sockets. But I don't want to do it unless I have to.
Read through the linked post especially the PDF How-To file. Yikes.
The wording of your question indicates you are not fully up to speed on this yet. Yikes again Good luck, Haya....
Link
 

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Discussion Starter #5
I believe this is a sensor code and not an indicator of real knock
I would Check the shielding continuity and disconnect/ reconnect the harness at the connector near the transmission and clean the engine and ECU grounds and battery cables at both ends. If you have access to a lab scope there is a test in the FSM to check the output.
if you actually have pinging and drivability issues it may be from excessive oil consumption through the PCV system due to sludge in the valve cover baffle. Several threads on that. If you decide to change the knock sensors you might want to address that issue too. You may want to do combustion chamber cleaning
No excess oil consumption. No pings or drive ability issues, other than it won't shift into OD after the light comes on. It still runs great. So how do I test the shielding continuity? What is the shielding? Do you mean if the wire casing is worn through and the wire is touching metal and the resistance is high because of that?
 

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Discussion Starter #6
scrambledtracker
My 2003 HL is experiencing the same problem. The fix is (not that) simple. I've even purchased the parts and e-torx sockets. But I don't want to do it unless I have to.
Read through the linked post especially the PDF How-To file. Yikes.
The wording of your question indicates you are not fully up to speed on this yet. Yikes again Good luck, Haya....
Link
Thank you! That is a great link to the write up and very good picture documentation. Yes it looks like a PITA but I either just drive the vehicle without overdrive, take it to a repair shop, or do it myself. I'm opting for the latter as the other options are not good! Sounds like most people do change the sensors too while they are in there, it just seems an added extra expense if it's just the harness.
 

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Did you see where he said you can cut the wires from the bad sensor and splice the wires from the good sensor into that harness? That saves the cost of the sensor and the job itself! Until the other sensor goes...
 

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Discussion Starter #8
Did you see where he said you can cut the wires from the bad sensor and splice the wires from the good sensor into that harness? That saves the cost of the sensor and the job itself! Until the other sensor goes...
OK, I guess I was focusing on the repair and weather or not to replace the sensors or just the harness. I've been leaning towards replacing everything if I have to dig in that far. So I like this wire splicing idea. Question, that post was for a Lexus, is the ECU for the 2002 Highlander behind the glove box and the wiring the same as in the pictures he shows? I'm all about trying this, only thing is, if the harness to the sensors that is under the manifold is what's throwing my codes and not the sensors, then splicing the wires won't help will it?
 

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This guy, after replacing the Knock Sensors then had all kinds of difficulties simply relocated one sensor. Link below.
I'm gonna try the Wiring Hack but if that does not do it my plan B is to relocate the sensor just like this guy did. Screw the idea of taking half the engine apart to get at a stupid sensor.
BTW- the same era Camry has the Knock Sensor mounted on the end of the cylinder head, takes about 5 minutes to change out a sensor. Cripes!.....Haya....
 

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Discussion Starter #10
This guy, after replacing the Knock Sensors plus kinds of difficulties simply relocated one sensor. Link below.
I'm gonna try the Wiring Hack but if that does not do it my plan B is to relocate the sensor just like this guy did. Screw the idea of taking half the engine apart to get at a stupid sensor.
BTW- the same era V6 Camry has the Knock Sensor mounted on the end of the cylinder head, takes about 5 minutes to change out a sensor. Cripes!.....Haya....
Great link, thank you! And wow, my brain hurts after reading all that! I did see similar hacks on you tube where a new short wire harness was spliced into a new relocated sensor, so the splice was in the harness not at the ECU. Either way it's better than spending the money on new sensors and tearing it all apart. Especially if you may get a new sensor that is bad! Mine was reading bank 2 malfunction, so I guess 1st thing for me to do is feed bank 1 sensor to pins 27 & 28 on the ECU. If that doesn't work, get a new short harness and relocate a new "dummy" sensor. I'm going to re read this a few more times to understand it all better before doing anything! I really do appreciate all the help here from everyone. In the meantime,on my 2nd vehicle I'm now driving, a 2000 silverado the blower fan has stopped working so no heat! When it rains it pours!
 

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Discussion Starter #12
Check for mice.
I had a Jeep the mice would fill the fan surround with dog food.
Got the chevy fan working for now, the wire connector was melted, a common problem I'm told. Temporary fix for now, new parts ordered. Now back to figuring out the Highlander.
 

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Discussion Starter #13
So after reading Endzone3's posts another time ( the last link Hayabusafalcon tagged) from what I understand, doing all the troubleshooting by making the jumpers for EB1 and EB2 is just to determine if the problem is the sensor or the short wire, or the other troubleshooting/testing is to see if the wire from EB 1&2 to the ECU is good, or testing the ECU itself to see if it is good. So if I assume it's a bad sensor or the wire from EB 1 and 2 to the sensors that is the problem, and assume the wire from EB to the ECU is good, and I have the code that sensor 2 bank 2 is bad, then all I really would need to do is splice the signal from the good sensor (bank 1) in wire 27 to the terminal 28 on the ECU. Does that sound correct? I know I should't assume things, but that seems the easiest thing to do, and if it doesn't fix it, not so hard to undo.
 

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Scramble: sounds right to me. Let's compare notes as we proceed. I'm gonna do the hack on Thursday or Friday. I'll post my results, Haya....
BTW- As long as I'm into the terminal blocks behind the glove compartment, I plan to run an extra single wire thru the firewall into the engine compartment. That way (if needed), I can mount a new sensor next to the motor mount on the passenger side. (Plan B as I mentioned before.) It's only a matter of inches between the motor mount and the terminal blocks so I' thinking a length of wire about 24 inches or so. I'll just leave the wire rolled up and zip-tied under the hood in case I need it later.
2nd BTW-I'm gonna disconnect the battery before I proceed. Just to be safe.
 

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Discussion Starter #15
Scramble: sounds right to me. Let's compare notes as we proceed. I'm gonna do the hack on Thursday or Friday. I'll post my results, Haya....
BTW- As long as I'm into the terminal blocks behind the glove compartment, I plan to run an extra single wire thru the firewall into the engine compartment. That way (if needed), I can mount a new sensor next to the motor mount on the passenger side. (Plan B as I mentioned before.) It's only a matter of inches between the motor mount and the terminal blocks so I' thinking a length of wire about 24 inches or so. I'll just leave the wire rolled up and zip-tied under the hood in case I need it later.
2nd BTW-I'm gonna disconnect the battery before I proceed. Just to be safe.
Haya, yes unhook the battery! I pulled the glove box and unplugged the terminals to see what had to be done then realized I hadn't unhooked the battery. I plugged them back in but didn't try and start it so I hope it's alright. Definitely let's let each other know our progress on this, I dont think I will be able to start mine until late next week or next weekend. I'm thinking the engine has to have at least 1 functional sensor or when it starts to knock it wont correct the timing. But as long as there is 1 working the ECU can be fooled by trying other terminals to 1 sensor.
 

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Discussion Starter #16
I will be using quick disconnects on the wires, probably the male/female spade connectors, possibly the bullet type, either way I need to make sure I have enough before starting. I was also thinking, instead of making the splice by the ECU where the wires are short and there's not much room to work, that the splicing could actually be made under the hood. Break out #27 and #28 wires from the harness, and instead of them going through the EB1 connector, splice them together right there. That would be terminals 1 and 2. I don't know what wires are in terminal 3 and 4, those would stay in the harness and still connect with the factory EB1 connector, only the sensor wires would be taken out and spliced there. Just have to remove the top of the air box and the snorkle that goes into the throttle body. Might have more room to work there. Just a thought.
 

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scrambled: I went ahead and installed the hack per the Lexus RX300 post. It works. I recorded the details on my previous post........
"Gonna need to do the knock sensors....anybody done the HACK? see post no. 9"
Haya....
 

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Discussion Starter #18
scrambled: I went ahead and installed the hack per the Lexus RX300 post. It works. I recorded the details on my previous post........
"Gonna need to do the knock sensors....anybody done the HACK? see post no. 9"
Haya....
Great news! I'm glad it worked. I will probably splice mine at the ecu also and not under the hood as I was considering. Still, if your one working knock sensors fails and you feed the signal from your "dummy" relocated sensor, when the engine does start to knock it will not sense it and the computer will not be able to compensate for that. It was also my #2 sensor which failed, as yours. If after I do the hack and the other fails I think I would go through the diagnostic procedure and find out if it's the wire or the sensor before deciding what to do. Hopefully I that wont be necessary! Again I'm glad this was successful for you and I hope to get at mine soon!
 

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The alternate sensor won't pic up a knock signature? Maybe it will. It's hard bolted to the engine block. Just a different location. It's basically a microphone. I looked at this and there are a host of mounting locations used by various engine manufacturers. They don't always put the sensors down in the V like Toyota did this time....
Besides, it's not like it's a race car. Or a turbo.
All the best, Haya....
 

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Discussion Starter #20
The alternate sensor won't pic up a knock signature? Maybe it will. It's hard bolted to the engine block. Just a different location. It's basically a microphone. I looked at this and there are a host of mounting locations used by various engine manufacturers. They don't always put the sensors down in the V like Toyota did this time....
Besides, it's not like it's a race car. Or a turbo.
All the best, Haya....
[/QUO Haya, You could be right on this, I dunno, I guess it was more of a question if it could still detect a knock. You have a good point in that it's mounted to a ridged location. BTW, great idea using a nut on it and mounting it like a bolt, rather than having to find the correct size drill bit and tap. Looks like I won't be getting to mine until later next week.
 
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