2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1274
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
* The engine speed is greater than 1,600 RPM.
* The ECM is controlling spark.
* DTCs P0326 and P0331 run continuously once the above conditions are met.
P0327, P0328, P0332, and P0333
* DTCs P0324, P0335, P0336, P0338, P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, P0393 are not set.
* The engine speed is greater than 1,960 RPM.
* The ECM is controlling spark.
* The increase in engine speed is less than a range of 1,400-3,700 RPM per second.
* The engine load is in the range of 35-65 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 knock sensor signal voltage that is not in the range of a predetermined engine noise level 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 a knock sensor signal voltage that is less than the predetermined minimum engine noise level for greater than 1 s or for a
cumulative of 10 s.
P0328 or P0333
The ECM detects the knock sensor signal voltage is greater than predetermined maximum engine noise level for greater than 1 s or for 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.
* With the knock sensor disconnected, the normal voltage measured from the knock sensor signal or the low reference circuit to ground is
between 2.30-2.80 V.
Reference Information
Schematic Reference
Engine Controls Schematics (LAU) (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/Connector End Views By Name)
Description and Operation
Knock Sensor System Description (See: Powertrain Management/Computers and Control Systems/Knock Sensor/Description and Operation)
Electrical Information Reference
