Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCADILLAC1993FLEETWOOD BROUGHAM V8-350 5.7LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMKNOCK SENSORTESTING AND INSPECTION
1993 Cadillac Fleetwood Brougham V8-350 5.7L
Knock Sensor: Testing and Inspection
1993 Cadillac Fleetwood Brougham V8-350 5.7LSECTION Testing and Inspection
DIAGNOSIS
Scan Tool
The Tech 1 scanner has several positions to check for diagnosing Knock Sensor (KS) circuit. "Knock signal" is used to monitor the input signal from the knock sensor. This position should display "YES" to indicate when a knock is being detected. Knock retard is the indication of how much the Engine Control Module (ECM) is retarding the spark.
Diagnostic Charts
Diagnostic Trouble Code (DTC) 43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to Chart C-5 Knock Sensor System Check. Chart C-5 Knock Sensor (KS) System Check
Scan Tool
The Tech 1 scanner has several positions to check for diagnosing Knock Sensor (KS) circuit. "Knock signal" is used to monitor the input signal from the knock sensor. This position should display "YES" to indicate when a knock is being detected. Knock retard is the indication of how much the Engine Control Module (ECM) is retarding the spark.
Diagnostic Charts
Diagnostic Trouble Code (DTC) 43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to Chart C-5 Knock Sensor System Check. Chart C-5 Knock Sensor (KS) System Check
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.