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.
1991 Mercedes Benz 560SECFACTORY OEM SERVICE PROCEDURE
Testing With On-Off Ratio Tester: Notes
NOTE:
Perform On-Off Ratio Test and record results. Proceed to appropriate TEST STEP as indicated in TROUBLE SHOOTING charts. See appropriate TEST STEP CHARTS and perform indicated circuit tests to repair vehicle:
- 6-cylinder models, see: TEST STEP CHARTS - 6-CYLINDER
- V8 models, see: TEST STEP CHARTS - V8
Factory Service Tools
Use the Manual With the Right Hardware
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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.