Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hi, my name is***** the batteries are good and you just get a click when turning the key I would have to suspect a fault with the starter motor. A voltage test will need to be performed at the starter to verify that voltage is present when turning the key. If there is voltage to the starter solenoid you will need to replace the starter.
It's located on the passenger side rear of the motor. You will need to gain access from underneath the car.
The solenoid and starter are one.
I can tell you how to bypass the starter relay from under the hood to test the starter. You will need a fused jumper lead.
The starter relay is the green relay located in the passenger side fuse box under the hood near the starter battery. Remove the relay and use your fused jumper lead to jump from terminal 30 to 87 in the relay box to test the starter. You can use a 25 amp fuse in your jumper lead. I've attached a picture below.
A fused jumper is just a wire lead with a fuse in the middle that you use to jump electrical circuits. An inline fuse holder works well for a jumper lead. You can crimp a couple of blade terminals on each end of the fuse holder and insert them into the slots where the relay plugs into. Jumping terminal 30 and 87 should activate the starter. I've attached a picture of an inline fuse holder below. You can use a 30 amp fuse in the holder.