leo_friedrich96
Mercedes SLC starting issue
Summary of the thread
A 2017 Mercedes SLC with a gasoline engine is experiencing starting issues, with an error indicating an interruption of Terminal 15 ignition positive. The problem is suspected to be due to a bad cable or plug, potentially involving the ignition switch, fuse box, or power supply causing a voltage drop to the starter solenoid. Suggestions include checking the fuse box and ignition switch wiring for continuity and voltage using a multimeter. The issue was resolved by repairing a corroded connector in the fuse box, costing 95€.
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4 comment(s)
leo_friedrich96 (community.author)
Thanks. When you say check the ignition switch wiring, what am I looking for? Is there a specific voltage I should expect, or a particular area prone to issues?
ida_wolf6
Use a multimeter and check the voltage at the ignition switch when you turn the key. It should be close to battery voltage, around 12.6V. A big drop means a bad switch or wiring. If you're not comfortable with electrical work, take it to a shop. It's a pain to trace these problems.
leo_friedrich96 (community.author)
I took it to a workshop. It was a corroded connector in the fuse box, causing a voltage drop. The repair was 95€. Thanks for the help!
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MERCEDES
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SLC
ida_wolf6
I had a similar problem in an old BMW 3 series. Check the fuse box thoroughly, especially the ignition fuses. Don't just look, use a multimeter to test for continuity. It could be a bad connection causing the voltage drop. Also, check the ignition switch wiring; it might be chafed.