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.
1985 Mercedes Benz 190D AutomaticFACTORY OEM SERVICE PROCEDURE
Switchover Valves
- Connect a volt/ohmmeter to connector of switchover valves and measure voltage at 1200 RPM, voltage should be approximately 12 volts. If voltage is okay, go to next test. If test is not okay, test electrical activation and replace control unit, if necessary.
- Connect Vacuum Tester (116 589 25 21 00) with "Y" fitting to switchover valve and check vacuum at 1200 RPM (switchover valve energized with 12 volts). Switchover valve should have approximately 19 in. vacuum. If test is okay, end of test. If test is not okay, test vacuum pump and replace switchover valve if necessary.
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.