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Matt, Engineer
Category: Mercedes
Satisfied Customers: 21851
Experience:  Mechanical Engineer with 23 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I am working on a 1998 mercedies e320 and the starter just

Customer Question

Customer: i am working on a 1998 mercedies e320 and the starter just clicks but won't start ad brand new starter
JA: Thanks. Can you give me any more details about your issue?
Customer: i am getting no power to the small wire on the starter but if i jump the starter relay it cranks. I tried swapping the k40 relay module with another known good one and still same thing. I have all the proper power and grounds to the relay but same thing
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Submitted: 1 year ago.
Category: Mercedes
Expert:  Matt replied 1 year ago.


If the 12V feed to the starter 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 part 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 replaced

one other thing to consider is that the immobiliser is faulty and preventing the starter from being enabled - however if the dash / ignition lights are on then this usually means that its off

Expert:  Matt replied 1 year ago.


do you still need help?

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Customer: replied 1 year ago.
I have 12v to the starter from the battery. The 12v ignition wire comes from the the k40 module were the starter relay is. As I said the starter cranks when the relay is jumped which tells me the wire is good from the relay module to the starter. I have proper voltage and ground to relay terminals when the relay is out but for some reason when the relay is in it sends enough voltage to light the test light for a split second to make the starter click and then goes away. That is were I am stumped, it just doesn't make sense.
Expert:  Matt replied 1 year ago.


if you haven't already then I'd check that the main earth connection is good as this sounds like there's a problem with this, might be worth just clipping on a jump lead between the engine block and battery earth to see if this helps at all

Customer: replied 1 year ago.
According to the power probe the engine has a good ground .
Expert:  Matt replied 1 year ago.


in that case I'd say the issue must be with the ignition switch? as if its not sending sufficient current to the K40 device to keep it switched in then there must a be a dirty contact or a short on the switch