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.
1987 Mercedes Benz 560SLFACTORY OEM SERVICE PROCEDURE
Deceleration Shutoff
- Connect on-off ratio tester to diagnostic socket. With engine at idle and operating temperature, tester needle should oscillate. If okay, test is complete. If not okay, go to step 2).
- Drive vehicle on road test. With engine above 2500 RPM, place shift lever in position "2" and decelerate. When vehicle decelerates (throttle valve closed) the on-off ratio should jump to about 80% and should restart the fuel injection below 1300 RPM (tester needle should oscillate). If not okay, check idle speed contact on throttle valve switch and TD signal. Go to step 3). If okay, test is complete.
- Test speed signal (speedometer). Check wire between idle speed control unit plug and electronic speedometer for continuity. Resistance should be zero ohms. If not okay, repair interruption. If okay, test is complete.
Factory Service Tools
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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.