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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53981
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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What would prohibit a 1979 Mercedes 450SL from starting. It

Customer Question

What would prohibit a 1979 Mercedes 450SL from starting. It gets power to the cylenoid but not enough voltage to make it start. You can jump across it and it turns the starter good, but it don't get enough voltage from switch to turn the starter. It gets enough to light the test light but not enough to start it. Vin #10704412052578
Robert H. Johnson
206 Boy Scout Road
Minden, LA 71055 Email***@******.*** (###) ###-####home (###) ###-####- cell
Submitted: 2 years ago.
Category: Mercedes
Expert:  Marty replied 2 years ago.

Hi Robert, voltage to the solenoid comes from the ignition switch then goes to the neutral safety switch on the transmission and then to the starter solenoid. You need to get a voltmeter and start taking some voltage readings. First measure the voltage at the solenoid with the wire connected to the solenoid and the key turned to the start position. Next move to the junction block on the passenger side inner fender and measure it there. Keep working your way back towards the ignition switch until you find your voltage drop. All tests need to be done with the circuit connected and the key turned to the start position. I suspect you either have a problem with the neutral safety switch or with the wiring from the switch to the starter. It's possible that you have a bad ignition switch. You just need to take your voltage readings and find out where in the circuit your voltage drops.

Let me know if you have any questions.

Marty

Expert:  Marty replied 2 years ago.

I sent you a phone offer if you would like me to call and help you with this.

Customer: replied 2 years ago.
Marty, I had already tried all of your suggestions. I am still stumped and do not know how to fix it.
Bob Johnson
Expert:  Marty replied 2 years ago.

Hi Bob, if you tried everything I suggested I will need to no whether you found voltage drop in the circuit or you didn't. I can help you get this sorted out but I will need to talk with you on the phone.