2010 Cadillac CTS Sedan AWD V6-3.6L Page 1327
The knock sensor is a piezoelectric device that produces an AC voltage of different amplitude and frequency depending on the level of engine
mechanical vibration. The knock sensor system monitors the knock sensor in order to determine if detonation or spark knock is present. If the
knock sensor system determines that excessive knock is present, the engine control module (ECM) retards the spark timing based on the signal
from the knock sensor system. The knock sensor produces an AC signal when specific frequencies are detected. The ECM then retards the timing
until knock is controlled.
In order to differentiate between normal engine noise and spark knock, the ECM samples the knock sensor signal. The ECM samples the knock
sensor signal for a certain length of time under different engine speeds and loads during non-cylinder knock events. This sampling is used to
determine a range of acceptable normal engine noise.
Conditions for Running the DTC
P0326 and P0331
* DTC P0324 is not set.
* The engine coolant temperature (ECT) sensor is warmer than 60掳C (140掳F).
* The engine speed is greater than 2,200 RPM.
* The increase in engine speed is less than 500-2,300 RPM per second.
* The increase in engine load is less than a range of 50-100 kPa per second.
* DTCs P0326 and P0331 run continuously once the above conditions are met for approximately 20 s.
P0327, P0328, P0332, and P0333
* DTC P0324 is not set.
* The engine coolant temperature (ECT) sensor is warmer than 60掳C (140掳F).
* The increase in engine speed is less than a range of 500-2300 RPM per second.
* The increase in engine load is less than a range of 50-100 kPa per second.
* DTCs P0327, P0328, P0332, and P0332 run continuously once the above conditions are met for approximately 20 s.
Conditions for Setting the DTC
P0326 and P0331
The ECM detects a short to ground or a voltage on the knock sensor signal circuits in 25 of 250 test samples. The condition exists for greater than 1
s or for a cumulative of 10 s.
P0327 or P0332
The ECM detects the knock sensor signal voltage is less than the calculated minimum for a predetermined engine noise level. The condition exists
during 2 consecutive tests, for greater 1 s or a cumulative of 10 s.
P0328 or P0333
The ECM detects the knock sensor signal voltage is greater than the calculated maximum for a predetermined engine noise level. The condition
exists during 2 consecutive tests, for greater 1 s or a cumulative of 10 s.
Action Taken When the DTC Sets
DTCs P0326, P0327, P0328, P0331, P0332, and P0333 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0326, P0327, P0328, P0331, P0332, and P0333 are Type B DTCs.
Diagnostic Aids
* Inspect the knock sensor for physical damage. A knock sensor that is dropped or damaged may cause a DTC to set.
* Inspect the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause a DTC to set. The knock sensor
should be free of thread sealant. The knock sensor mounting surface should be free of burrs, casting flash, and foreign material.
* The knock sensor must be clear of hoses, brackets, and engine electrical wiring.
* The normal voltage on the knock sensor signal and low reference circuits is 2.43 V when the knock sensor is disconnected.
Reference Information
Schematic Reference
Engine Controls Schematics (LLT) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics
(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
