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Re: I need Info & photos of how to replace the Knock...
They sell the books for your vehicle at the parts store and I think it is called a Haynes Suburban, GMC Truck Repair Book cost between $14 to $20. That way you will have the pictures in front of you while you work. I am really not sure of the name of the book.
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Check engine light on ? What code ? There are many different (DTC'S) - diagnostic trouble codes that can set for knock sensors ! There all don't mean that you replace the sensor .
DTC P0324: Knock Sensor (KS) Module Performance
DTC P0325: Knock Sensor (KS) Circuit Bank 1
DTC P0326: Knock Sensor (KS) Performance
DTC P0327: Knock Sensor (KS) Circuit Low Bank 1
DTC P0328: Knock Sensor (KS) Circuit High Bank 1
DTC P0330: Knock Sensor (KS) Circuit Bank 2
DTC P0332: Knock Sensor (KS) Circuit Low Bank 2
DTC P0333: Knock Sensor (KS) Circuit High Bank 2
The knock sensor (KS) system enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The sensors are located below each cylinder head on the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The control module adjusts the spark timing based on the amplitude and the frequency of the KS signal. The control module receives the KS signal through 2 isolated signal circuits. The control module learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The control module should monitor a normal KS signal within the noise channel.
Knock Sensor Replacement - Bank 1
Remove the exhaust manifold lower heat shield. Refer to Exhaust Manifold Lower Heat Shield Replacement.
Disconnect the engine wiring harness electrical connector (1) from the bank 1 knock sensor (2).
Loosen the knock sensor bolt and remove the knock sensor.
Knock Sensor Replacement - Bank 2
Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
Remove the engine oil filter. Refer to Engine Oil and Oil Filter Replacement .
Lower the vehicle.
Disconnect the engine wiring harness electrical connector (2) from the bank 2 knock sensor (3).
Loosen the knock sensor bolt and remove the knock sensor.
Hi John, The knock sensors on both banks are fitted as closely to the cylinder head as possible. The knock sensors 'listen' to the ignition and adjust spark timing accordingly. They are fitted onto the hottest place on the engine and consequently the cables often get heated and hardened and easily break. The sensor is usually under the intake manifld (making it fairly hard to find, but it will be there. Regards John
On both cars the knock sensor is located in the intake valley.
the computer receive signals if engine knocking and adjust the timing till stop.Before replace the sensors make sure the engine have no other misfire ,bad gas or vacuum leak.plug scan tool and read the code.Only circuit problem will be a true knock problem. Inspect all wire connectors before start taking a part.
The knock sensor detects internal engine knock and retards timing accordingly . If a code is set for it, replace it and make sure the harness connector is in good shape, always a good idea to replace the pigtail end when doing the sensor cause sometimes its hard to tell
Check the wiring harnesses for bare or brittle spots. If none are found replace the spark plugs, all of them and spark plug wires. I know these are still fairly new but that is the next step. If you have over 60,000 miles on the vehicle it could be an issue with the timing chain but my experience tells me replace the crank Position sensor first if none of the other steps yield any results. Because these vehicles come with the power train warranties they do you can't really trust the Dealer Mechanics because they will do anything they can to prolong this to get the vehicle out of warranty.
The most likely cause of your code is a bad rear knock sensor. You should check the knock sensor wiring harness for corrosion. But if that checks out the sensor will have to be replaced. The knock sensor is under the intake manifold, although it's not too difficult to remove. Both knock sensors should be replaced along with the wiring harness, just because of labor involved in gaining access to the sensors. You could try clearing the code, it may stay off for a long time.
Forgive me for asking, but are you sure you replaced the knock sensors? They are underneath the intake plenum. I'm just wondering if maybe you replaced the Oxygen sensors by accident. Anyway, so that you know, this is a very common problem (the knock sensors). Gm has issued a bulletin, something to do with the rear knock sensor under the intake getting contaminated by water, and they recommend a new sensor installed with silicone around the gasket to protect it. Also, the wiring harness is particularly tasty to rodents and they get in there and eat the insulation and wires! You have to inspect the harness carefully when you have the intake off because you can't see it when it's all together. Seen this twice now.
Need to remove the upper and lower air intake manifold. There are two knock sensors for the front and rear pistons banks. If you plan to do this yourself it is about 1 to 2 hours. While you are at it, there is a short coolant bypass hose sitting in the same spot, replace it. Another problem with the knock sensor is the wire harness used to connect the two knock sensors into one connection sometimes wears out and contacts the metal on the engine causing false signals to the ECM, so replace this cable also.
Just did this last summer on my 99 ES300. Pretty easy.
On a 6 cylinder, the knock sensor is located under the intake manifold, on the inside edge of the cylinder block. You must remove the entire intake manifold assembly to access the knock sensor. If you are replacing it, it would be very advisable to replace the sensor AND the extension wire from it to the main harness. I have observed that the wire extensions become brittle over time, and they fail with regularity.