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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3663
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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I have a2006 CLS500, 2006, i changed the brake booster and

Customer Question

i have a2006 CLS500
JA: What year is your CLS500?
Customer: 2006
JA: Are you fixing your CLS500 yourself? What have you tried so far?
Customer: i changed the brake booster and the car will not start
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: yes brand new charged battery recommended from Mercedes
JA: Anything else you want the mechanic to know before I connect you?
Customer: car doesn't click during normal startup, when clicking the key into engine run position no thing happens
Submitted: 18 days ago.
Category: Mercedes
Customer: replied 18 days ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Lou P. master tech replied 18 days ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. master tech replied 18 days ago.

are you saying the car does not even crank?

do you have a meter to check a few things?

Customer: replied 18 days ago.
i am have a volt meter and no the car doesn't crank or click when when going into the engine start position.
Expert:  Lou P. master tech replied 18 days ago.

ok, there shouldnt be anything up there that stops the engine from cranking, when the key is turned on can you see if the dash shows the correct gear?

Expert:  Lou P. master tech replied 18 days ago.

i will be on more tonight more consistent, sorry for any delays with my messages.

Customer: replied 18 days ago.
it shows the correct gear, I replaced the brake switch and I am picking up the starter relay.
Expert:  Lou P. master tech replied 17 days ago.

ok so this may be a little backwards but i want you to test for power at the starter solenoid when cranking, it will be a violet wire, maybe by coincidence the starter failed. also did you take loose any ground wires near the brake booster? can you walk me through what you removed to access it?

Customer: replied 17 days ago.
Disconnected the wires from the underdash, removed the brake switch and housing. Removed brake pedal retaining screw, removed the brake booster retaining nuts, inside hood, disconnected the two metal brake lines, two rubber houses and both electrical connections, one on top and one on back
Customer: replied 17 days ago.
Installation was reverse order
Customer: replied 17 days ago.
I didn't loosen any ground wires.
Customer: replied 17 days ago.
Is it possible that in the installation I pinched a wire from the brake booster that would effect starting of the vechicle? Specifically the wire connection on the back of the brake booster next to firewall?
Expert:  Lou P. master tech replied 17 days ago.

ok , it is possible BUT there are not many items that run back there, hmmm, ,

Expert:  Lou P. master tech replied 17 days ago.

does the car come to life with the key turned? does all functions work except the cranking of the car?

Customer: replied 17 days ago.
The wiring harness that connects to the brake booster behind the brake fluid reservoir? Does that wiring harness have anything to do with enabling the vechicle to start or is that just the brake switch?
Customer: replied 17 days ago.
in switch position 1 and 2 the car instrumentation all illuminates
Expert:  Lou P. master tech replied 17 days ago.

that should just be for the brake booster solenoid. and travel sensor. do you have any pictures?

Customer: replied 17 days ago.
I inspected the wiring on the brake booster wiring harness and all wires appear to be intact and no visible brakes or cuts in the physical wiring
Customer: replied 17 days ago.
To take pictures I would have to remove the brake booster
Customer: replied 17 days ago.
The crack sensor had been replaced a month prior and the brake switch 2 days ago.
Customer: replied 17 days ago.
When attempting to start the car all instrumentation lights illuminate. No clicking, grinding, spinning noises coming from the starter.
Expert:  Lou P. master tech replied 17 days ago.

ok, so lets look at this as a new problem then, see if we can get power at the starter when cranking and go from there.

Customer: replied 17 days ago.
Where is the starter located? What do you want me to do? Voltage meter to violet wire at positive lead post?
Customer: replied 17 days ago.
Just to be sure, there is no element of the brake booster wiring harness located on the back side of brake booster that enables or prevents the car to start, correct?
Expert:  Lou P. master tech replied 17 days ago.

correct, there should not be any harness near the brake booster that has to do with starting the car, all important wiring is right inside of the fuse box case.

if you can get a test light, you hook the test light to ground and poke the test light to the starter solenoid wire which should be violet or purple what have you, and when cranking the light should light up if it does not then we are not getting a signal to the starter and need to focus elsewhere, if anything i think you need to recheck all the disconnected wiring under the dash that you touched or unplugged and check for bent pins and loose connections.

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