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 MANUALSCADILLAC1991FLEETWOOD FWD V8-300 4.9LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMIGNITION CONTROL MODULEDESCRIPTION AND OPERATIONENGINE SPEED SIGNAL
1991 Cadillac Fleetwood FWD V8-300 4.9L
Engine Speed Signal
1991 Cadillac Fleetwood FWD V8-300 4.9LSECTION Engine Speed Signal
The engine speed signal comes from a seven terminal High Energy Ignition (HEI) module in the distributor. Pulses from the distributor are sent to the PCM/ECM where the duration between these pulses are used to calculate engine speed. The PCM/ECM adjusts spark advance and sends a signal back to the distributor.
RENDER: 1.0x
NO RELATED
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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.