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 MANUALSCADILLAC1985FLEETWOOD BASE, 4D LIMOUSINEREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISDFI BCM TESTS W/CODES - FWDFIXED SPARK MODE PROCEDURE
1985 Cadillac Fleetwood Base, 4D Limousine
Fixed Spark Mode Procedure
1985 Cadillac Fleetwood Base, 4D LimousineSECTION Fixed Spark Mode Procedure
- Purpose of test is to verify proper adjustment of spark timing. In this test procedure, the ECM commands a fixed spark advance of 10° and prevents EGR operation under the following conditions: Engine running and warm (parameter "P.0.4" above 185°F/85°C), engine speed below 900 RPM and transmission in "P".
- Exit diagnostics (press "Auto") and jumper pins "A" and "B" (circuit Nos. 150 and 451) of ALDL connector. See Fig 1 . The SERVICE SOON" light may begin to flicker when pins are jumpered.
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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.