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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 22256
Experience:  BEng hons Mech engineering, in auto industry 22 years
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2002 Mercedes C180 Coupe Auto. New battery fitted sometimes

Resolved Question:

2002 Mercedes C180 Coupe Auto. New battery fitted sometimes starts and drives perfectly, other times lights come on but does not respond when key is turned
Submitted: 2 years ago.
Category: Mercedes
Expert:  Matt replied 2 years ago.
Hello If the car's not cranking then first check that the main battery cables are on tight and the terminals are clean and bright. Do the same for the engine / gearbox earth strap.Then follow the main positive lead back to the engine and down to the starter motor, and check the connection at this end as well. There should also be a small wire to the motor which should have 12V when you're turning the ignition switch to crank. If the 12V isn't there, check back along this wire for damage to the insulation or corroded connections This 12V feed comes directly from the ignition switch so this may be faulty and need replacing Check the resistance of the main positive lead that runs down to the motor as anything more than a few ohms and it should be replacedDon't forget to try a jump start from another car / battery as its possible the battery is poor, if you have a voltmeter a healthy battery should read 12.7+V
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