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.
1988 Mercedes Benz 560SLFACTORY OEM SERVICE PROCEDURE
Rpm Shut-Off
- Connect vacuum tester with "Y" fitting to actuator for vacuum control flap. With vehicle on a chassis dynamometer, test vehicle in high gear (5th gear or "D") at partial load. If below 56 MPH, vacuum should be about 12 in. Hg. Above 56 MPH, vacuum should be zero. If okay, test is complete. If not okay, go to next step.
- Test electrical activation of switchover valve. Connect multimeter to connector of switchover valve and repeat test. If voltage (about 12 volts) is indicated at speeds above 56 MPH, test electrical activation of switchover valve. Replace defective parts, if necessary. If there is no voltage, replace switchover valve.
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.