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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3739
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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2002 Mercedes e320 it has a brand new battery holding 12.7

Customer Question

2002 Mercedes e320 it has a brand new battery holding 12.7 volts. alt when running 13.5. here is the problem the key will not turn unless you put jumper cables on it . or battery charger. it makes no sense
Submitted: 9 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 9 months ago.

Hello. Most times the ground wire in this model can fail. Check the resistance of the ground wire from the battery to the body. See if that helps. That is what this scenario sounds like. Let me know and we can check and try other things. Lou P.

Expert:  Lou P. master tech replied 9 months ago.

When you jumped the car if you put the negative to ground and the positive to the battery then you bypassed the negative cable which would also tell me that is the issue. Let me know. Lou P

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