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 300DFACTORY OEM SERVICE PROCEDURE
Rpm Signal
- Connect multimeter to terminals No. 1 and 2 of EDS test connector. Connector is located next to battery. Set multimeter to voltage scale. Run engine at idle speed. If nominal value is greater than 2.8 volts, voltage signal is normal. If voltage is less than 2.8 volts go to next step.
- Turn engine off. Disconnect ring gear speed sensor connector. Connect multimeter and set to ohm scale. Check resistance at connector terminals. Resistance should be between 1700-2100 ohms. If resistance is not to specification, replace ring gear speed sensor. Ring gear speed sensor is located at rear of oil pan.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.