Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Knock sensor 1 circuit / Circuit description
Toyota Corolla (E120): Circuit description
A flat type knock sensor (non–resonant type) has the structure that can detect the vibration in a wider band of frequency from about 6 khz to 15 khz and has the following features.
Knock sensors are fitted on the cylinder block to detect the engine knocking.
The sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, the ignition timing is retarded to suppress it.
Hint
: if the ecm detects the dtc p0325, it enters the fail–safe mode in which the corrective retarded angle value is set to the maximum value.
Reference: inspection using the oscilloscope.
- After warming up run the engine at 4,000 rpm, check the waveform between terminal knk1 and eknk of the ecm connector.
Monitor description
The knock sensor, located on the cylinder block, detects spark knock. When spark knock occurs, the sensor picks–up vibrates in a specific frequency range. When the ecm detects the voltage in this frequency range, it retards the ignition timing to suppress the spark knock.
The ecm also senses background engine noise with the knock sensor and uses this noise to check for faults in the sensor. If the knock sensor signal level is too low for more than 10 seconds, and if the knock sensor output voltage is out of normal range, the ecm interprets this as a fault in the knock sensor and sets a dtc.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Wiring diagram
Other materials:
Road test
1. Problem symptom confirmation
Taking into consideration the results of the customer problem analysis,
try to reproduce the symptoms
of the trouble. If the problem is that the transaxle does not shift up,
shift down, or the shift point is too
high or too low conduct the following road ...
Replacement
Hint: components:
1. Remove radiator grille sub–assy
2. Remove front bumper cover
3. Remove lh headlamp assy
Remove the 3 bolts.
pull out the headlight assy lh forward, then disconnect
the bracket of body side.
Release the claws and disconnect the connectors as
sh ...
Replacement
Hint: components:
1. Remove floor shift shift lever knob sub–assy
2. Remove console panel upper
3. Remove parking brake hole cover sub–assy
4. Remove console box sub–assy rear
5. Separate floor shift cable transmission control shift
Separate the end of the shift cable from the ...