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
Gasoline System Testing: TD-Signal
- Disconnect CIS-E control unit plug. Start engine. Check voltage between terminal No. 25 of control unit plug and ground. Voltage reading should be between 6-12 volts. If okay, test is complete. If not okay, proceed to next step.
- Unplug fuel pump relay. Check wire between terminal No. 10 of relay plug and terminal No. 25 on CIS-E control unit plug for continuity. Resistance reading should be zero ohms. If resistance is zero ohms, check wires to ignition control module for continuity.
- If resistance is not as specified in step 2), repair open circuit in wiring harness.
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.