Knock sensor low voltage...

[bowtiefreak]

I get this code if I jump on a highway and cruise for a bit, never around town or anything. Sounds like a bad sensor right?

 

[SunlitComet]

code number please.

 

[bowtiefreak]

damn it, I cleared it. I will post it soon....just need to hit the highway again.

 

[SunlitComet]

Of course you did.

 

[bowtiefreak]

0327

Got it this morning during my commute on side streets which was a first for that. Knock sensor 1 low voltage. Now what could it be?

 

[SunlitComet]

Back at work. Will pull up when I get home in the morning.

 

[SunlitComet]

P0327

DTC P0327 Knock Sensor Noise Channel Low Voltage (1 Of 2)

DTC P0327 Knock Sensor Noise Channel Low Voltage (2 Of 3)

DTC P0327 Knock Sensor Noise Channel Low Voltage (3 Of 3)

Knock Sensor Circuit



CIRCUIT DESCRIPTION
The Vehicle Control Module (VCM) uses the Knock Sensors in order to detect engine detonation. This allows the VCM to retard the Ignition Control (IC) spark timing based on the Knock Sensor (KS) signal the VCM receives. The circuitry within the knock sensor pulls down the VCM-supplied 5 volt signal, so that under a no knock condition the signal on the KS circuit measures about 1.3 volts. The knock sensors produce an AC signal that rides on the 1.3 volts DC. The signal's amplitude and frequency are dependent upon the amount of the knock being experienced.

The VCM determines whether the knock is occurring by comparing the signal level on the KS circuit with a voltage level on the noise channel. The noise channel allows the VCM to reject any false knock signal by indicating the amount of normal engine mechanical noise present. The normal engine noise varies depending on the engine speed and load. When the VCM determines that an abnormally high noise channel voltage level is being experienced, a DTC P0326 sets. This DTC is a type B DTC.

CONDITIONS FOR SETTING THE DTC

Knock Sensor Update Test

• The timing retard is no more than 0°.
• System voltage is greater than 10 volts but no more than 17.1 volts.
• The Engine Coolant Temperature sensor is greater than 60°C (140°F).
• Engine run time is greater than 2 minutes.
• Engine speed is between 500 RPM and 900 RPM.

Active Noise Channel Test

• No Engine Coolant Temperature (ECT) DTCs set.
• No Throttle Position (TP) sensor DTCs set.
• The Knock Sensor update test is complete.
• The ECT is at least 60°C (140°F).
• The engine speed is between 2000 RPM and 3000 RPM.
• The throttle angle is at least 5.8%.
• The engine has been running for at least 2 minutes.
• The system voltage is greater than 10 volts but no more than 17.1 volts.
• The timing retard is no more than 0°.
• The VCM is monitoring a ESC noise channel voltage level is below 0.5 volt.

ACTION TAKEN WHEN DTC SETS

• The VCM will not illuminate the Malfunction Indicator Lamp (MIL) .
• The VCM will store the conditions which were present when the DTC set as a Fail Records data only. This information will not store as Freeze Frame Data.
• The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is likely to occur. The calculated value will vary based on the engine speed and load.

CONDITIONS FOR CLEARING THE MIL/DTC

• A history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
• The scan tool Clear Info function or disconnecting the VCM battery feed can clear the DTC.

DIAGNOSTIC AIDS
Check for the following conditions:

• A poor connection at the VCM. Inspect the knock sensor and the VCM connectors for the following items:
• Backed out terminals.
• Broken locks.
• Improperly formed or damaged terminals.
• A misrouted harness. Inspect the knock sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads.
• Improper Knock Sensor torque specification. Torque the knock Sensor to 19 Nm (14 lbs. ft.) .

Review the Fail Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

1. Ensures that the fault is present.

1. Ensures that the knock sensor is capable of detecting detonation.

 

[bowtiefreak]

wiring looks good to me. I am curious if I should just replace this bad boy

 

[electro]

I am getting a similar code on my 2002 suburban.
On my truck apparently water gets between the engine block and manifold and corrodes the sensor. I bought 2 new sensors and 1 new manifold gasket (manifold gasket is not reusable) so i am currently planning on replacing both sensors and just being done with it. Also removing some foam pad thats under the manifold and using RTV sealant to build a dam/wall to stop water from getting into that area.

The sensors were not cheap and the damn gasket is the same price as on sensor. Because of the cost of the gasket i figure ill just do both sensors and not pay for the 2nd gasket later. it looks like a fun job, remove the entire manifold with injectors and all..

 

[bowtiefreak]

On the GMT 400 trucks it is one sensor on the side of the block. Install is simple.