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 MANUALSCADILLAC1997SEVILLE SLS V8-4.6L VIN YREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMDESCRIPTION AND OPERATIONIGNITION SYSTEM OPERATING MODES
1997 Cadillac Seville SLS V8-4.6L VIN Y
Ignition System Operating Modes
1997 Cadillac Seville SLS V8-4.6L VIN YSECTION Ignition System Operating Modes
Ignition Control Spark Mode
There are two modes of ignition system operation: PCM mode and Ignition Control Module (IC Module) mode. In IC Module mode, the ignition system operates independently from the PCM. The ignition control module maintains a base ignition timing of 10° BTDC and is able to change this ignition timing slightly with increased engine speed. IC Module mode is in effect whenever an ignition control fault is detected while the engine is running and it will have a noticeable effect on driveability. In PCM mode, the PCM controls the ignition timing. The PCM calculates the desired ignition timing based on information it receives from the input sensors.
There are two modes of ignition system operation: PCM mode and Ignition Control Module (IC Module) mode. In IC Module mode, the ignition system operates independently from the PCM. The ignition control module maintains a base ignition timing of 10° BTDC and is able to change this ignition timing slightly with increased engine speed. IC Module mode is in effect whenever an ignition control fault is detected while the engine is running and it will have a noticeable effect on driveability. In PCM mode, the PCM controls the ignition timing. The PCM calculates the desired ignition timing based on information it receives from the input sensors.
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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.