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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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I have a 2008 Mercedes C300. My girlfriend hit something in

Customer Question

I have a 2008 Mercedes C300. My girlfriend hit something in the drivers front. It needs a new fender, hood, headlight and bumper. Now SRS Malfunction Service required light is coming up and the car will not start. The airbag did go off. I was told I need a new air bag and fuse box assembly. Then after that I have to take it to the dealership to get the computer reset. Is that all that needs replacedto get he car started again? The airbag and fuse box assembly
Submitted: 4 months ago.
Category: Mercedes
Customer: replied 4 months ago.
Expert:  Chad Farhat replied 4 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 4 months ago.

Hey how are you

What we need is Star Mercedes Scanner to retrieve fault codes ,the SRS air bag should not make it no start ,most likley the anti theft is triggered on .

Most likley you do not have that scanner available ,lets try a Master Reset first and we go from there ,

But yes that is true on scanner you need the dealer scanner to program the air bag and air bag module i believe you meant not fuse box :) to get it programmed

Master reset Procedure

1- Disconect Battery Cables ( Negative & Positive Cables )you can use any electrical wire as an extension if battery cables don't reach .

2- Hold cables Together for 60 secs ,then let go

3- Wait 15 minutes

4- Make sure all doors are closed

5- Reconnect battery Cables

6- Lock & unlock the vehicles using the key from driver door side (if you have a key fob with no blade key, just lock & unlock using the key fob buttons)

7- Enter the vehicle and attempt to start

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 4 months ago.
I've had the negative terminal off the car for a while so the battery didn't die can I start the procedure holding the positive negative together even though the negative has been off
Expert:  Chad Farhat replied 4 months ago.

yes you can ,but make sure our battery has a good 12 volt before you connect it back after the 15 minutes , charge it if need be

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 4 months ago.

Correction, I apologize

This model has a Pyrotechnics separator inside that kills power to the engine, so that is correct on that my mistake

Chad

Customer: replied 4 months ago.
OK I tried that procedure and the car would not start. Here is a picture of the damage and there looks like a little yellow sensor and then there are a couple bare wires I'm not sure if that has anything to do with it but either way what should I try next
Expert:  Chad Farhat replied 4 months ago.

well these wires needs to be repaired and retest

that is our front crash sensor ,anything yellow plug is airbag components

you will still need a Star Scanner or equivelat after that repairs

Customer: replied 4 months ago.
OK where do the two wires connect to and does that crash sensor need to be replaced?
Expert:  Chad Farhat replied 4 months ago.

yes and yes ,the proper way to do this is to get it scanned and retrieve fault codes and scanner will be needed at the end, I don't know what else deployed , with out these things you want be able to complete the repairs

Customer: replied 4 months ago.
Can my snapon scanner retrieve the codes or does it have to be done by a dealer
Expert:  Chad Farhat replied 4 months ago.

Yes if you have the European software in it and is up to date to 2008 at least

Customer: replied 4 months ago.
Ok just got a scanner. I will send you all the faults and then what each one reads
Customer: replied 4 months ago.
First here is the main list from auto scan
Customer: replied 4 months ago.
1. CGW-Central gateway. Fault 5Click on read codes
Customer: replied 4 months ago.
2. EZS-Electronic Ignition Switch. Fault 1Clicked on read codes
Expert:  Chad Farhat replied 4 months ago.

okay I got all the fault codes but is it possible to clear them all now , I got a record of them and and rescan and tells me what comes up now as current not history

and at this time nothing has been changed n it or the fuse box has and been programed ?

Customer: replied 4 months ago.
3. ME 9.7-Motor electronics 9.7. Fault 9Clicked on read code
Customer: replied 4 months ago.
The only thing that has been changed is I put in the new airbag in the steering wheel. So you want me to clear out every code right now and then re-auto scan it?
Expert:  Chad Farhat replied 4 months ago.

all these are what we call collateral codes cause by a few fault codes or one, we know we have an air bag issue and fuse box but the rest will clear after the repairs

yes clear fault codes and tell me what comes up

Customer: replied 4 months ago.
Ok I reset all the codes and did a rescan. Here's what came up. The only thing I did to the car is take the old airbag out and put on the new one.
Expert:  Chad Farhat replied 4 months ago.

Press on #4 ,first image ,ME motor electrconis 9.7 , click on that what is the fault number that shows next screen

Customer: replied 4 months ago.
When I click on read codes this is what comes up
Customer: replied 4 months ago.
When I click on ME 9.7-motor electronics 9.7. These are the options my scanner gives me
Expert:  Chad Farhat replied 4 months ago.

I m not sure I m not used to this scanner you are using , I will op out of your question and open it for other expert to assist you it

Just dont reply back to me since it will lock the question back to me and other expert want see it to assist you ,just wait and an expert will pick it up

good luck with it

Chad

Customer: replied 4 months ago.
Ok now it's saying pass no fault for the ME 9.7 Motor electronics 9.7
Expert:  Marty replied 4 months ago.

Hi, my name is***** helped you with this problem the other day. Have you replaced the F32 pre-fuse yet? The car won't start until the pre-fuse is replaced.

Customer: replied 4 months ago.
I need to order the whole fuse box correct not just one little fuse? Also where is this fuse box located and how do I replace it? I ordered one on eBay.
Expert:  Marty replied 4 months ago.

Correct, you need the entire fuse box and it can't be from a car that has had the air bag deploy or it won't be any good.

Customer: replied 4 months ago.
The fuse box is good not from a car that had the airbag deployed. Please send me the steps to replacing it and after I'm done replacing it will the car start or do I have to get something reset
Expert:  Marty replied 4 months ago.

Click on the attachment for the replacement procedure. After replacing the pre-fuse you just erase the fault codes and the car will start.

Let me know if you need anything else. Please remember to rate my service in order for the website to credit me for helping you today.

Customer: replied 4 months ago.
OK I went over the steps and they are Very confusing. I'm going to need more help the only thing I could figure out is taking the cover off and there are three wires bolted to the top I took those three wires off and now I am stuck
Expert:  Marty replied 4 months ago.
Where are you having difficulty?
Customer: replied 4 months ago.
I took the top plastic piece off and then unbolted the three thick wires on the top. Now I'm stuck and not sure what to do next
Expert:  Marty replied 4 months ago.
You need to unclip the box by pulling out the locks at the B arrows.
Expert:  Marty replied 4 months ago.
Use a small screwdriver. Once you pry out the lock tabs you can slide the box up out of the guides.
Customer: replied 4 months ago.
OK what do I do after I pull the box up? Second picture I sent you our two wire connections on the side of the box not sure how to remove those but first what is the next step after I pull the box up?
Expert:  Marty replied 4 months ago.
You will just disconnect the remaining wires and connectors and exchange the fuse box.
Expert:  Marty replied 4 months ago.
It may be easier if you transfer one cable at a time from the old box to the new one.
Customer: replied 4 months ago.
OK I got all the connectors off except for the yellow one maybe it's a sensor I don't want to break it how do you take that off
Expert:  Marty replied 4 months ago.
That one should disconnect at the other end of the wire harness.
Customer: replied 4 months ago.
the new fuse box it should have that sensor and wire coming off of it
Expert:  Marty replied 4 months ago.
Correct
Expert:  Marty replied 4 months ago.
Correction, I need to recheck whether or not the yellow fuse comes with the box. You can remove the fuse by pulling out the round center to unlock it.
Expert:  Marty replied 4 months ago.
I can recheck in the morning. I can't get to the catalog from my iPad.
Customer: replied 4 months ago.
Please explain a little bit better when you say call out the round center to unlock it. I just don't want to break anything
Customer: replied 4 months ago.
Pull* not call
Expert:  Marty replied 4 months ago.
click on the image below.
Customer: replied 4 months ago.
Will it pull up by using my fingers or do I need a screwdriver
Expert:  Marty replied 4 months ago.
A thin screwdriver blade would help.
Expert:  Marty replied 4 months ago.

Ok, you will also need to order the wire harness repair kit for the prefuse. The part number is ***** 440 55 07 and can be purchased from the Mercedes dealer. The new part will need to be spliced into the existing wire harness using solder connectors. The solder connectors are part number 001 546 99 41 (2 required). The part comes with more wire than is needed. You can cut and splice the vehicle wire harness at any convenient spot in the harness.

Customer: replied 4 months ago.
Why all of a sudden do I need this now? Will this cause the car not to start? I just need to get the car started right now
Expert:  Marty replied 4 months ago.

It should have been with the used fuse box but since it was not included you will need to order it from the part from Mercedes. Yes, it will cause the car not to start.

Expert:  Marty replied 4 months ago.

I see that you left Lou a negative rating on the same question for trying to help you. Lou has a point. We spend a lot of time trying to help customer's with their problems at a fraction of what it would cost at the shop. You should at least rate our service in order that we get paid.

Customer: replied 4 months ago.
Fuse box I ordered is brand-new and will be arriving today
Customer: replied 4 months ago.
Lou does not have a point I pay money for an expert to answer my questions that's what the website is for. If some questions are more detailed than others expert still has to answer them they do not get to pick and choose easy or more detailed questions that's not fair to the customer
Customer: replied 4 months ago.
back to the question the brand-new fuse box that I ordered does it have the wire harness or does it not because it's new?
Expert:  Marty replied 4 months ago.

Not sure without seeing it. If it is not included I would try reusing the yellow harness before ordering a new one. The service manual is not clear as to whether it also needs to be replaced.

Customer: replied 4 months ago.
OK I will get back to you when I install the new fuse box. So install it then use my scanner to erase the codes and it should start
Expert:  Marty replied 4 months ago.

Correct. And if you still have a no start and fault code 9CFE won't clear in the air bag module you will need to replace the harness.

Customer: replied 4 months ago.
OK I installed the new fuse box. Raced the codes. 9CFE code erased and my scanner is still hooked up and I tried starting the car and it wouldn't start do I have to take the scanner off and take the key out or disconnect the battery
Customer: replied 4 months ago.
OK code 9CFE I erased and then I rescanned the whole thing and the same code is still gone. It doesn't come up anymore. Under airbag 9C76 and 9C58 still show up. So now that the 9CFE does not come up in the car will not start what next
Customer: replied 4 months ago.
I took the broken headlight out and I see two wires a green and brown ones that are broken from somewhere. Also it looks like a sensor sitting there in the connectors for that headlight. Would any of this effect the car from not starting
Customer: replied 4 months ago.
Expert:  Marty replied 4 months ago.

No it should start with the scan tool hooked up. Try starting the car a few times then rescan it and see what you have for codes.

Customer: replied 4 months ago.
I am re-scanning the car right now. Other question is the key five is not locking or unlocking the doors I'm guessing the battery is dead well that have anything to do with the car not starting I take the little key out and manually opened up the drivers door but I didn't know if there was some kind of security system making it not start
Customer: replied 4 months ago.
Ok 3 faults come up.
ME 9.7-Motor electronics 9.7 I click on read codes and it says everything is OK and then when I clicked back it says passed no-fault
Customer: replied 4 months ago.
AB-AirbagI click on read codes and this is what comes up
Customer: replied 4 months ago.
OCP-Overhead control panelI click on read codes and this is what comes up
Expert:  Marty replied 4 months ago.

I don't see anything there that would cause a no start. Perhaps a factory scan tool would show something different. At this point you will need to start testing the signal to the starter to see if it is getting power when you turn the key to start.

Customer: replied 4 months ago.
OK how do I test the signal to the starter?
Customer: replied 4 months ago.
I called the dealer and they said it would be $183 for them to do a diagnostic on the car and if something needs program that would be included. When I replace the airbag and the fuse box does something have to be reset or programs by the dealer only or are they just trying to get me to come in?
Expert:  Marty replied 4 months ago.

To test the starter you would need to get down to the starter motor and measure the voltage on the small wire to the starter when the key is turned to the start position. I don't see any fault codes on your scan tool that would prevent starting. The factory scan tool may turn up something different. Usually the only codes that will keep the car from starting is the 9CFE code and that one seems to be gone now.

Expert:  Marty replied 4 months ago.

You should also make sure that there is 12V at the big wire on the starter and on the alternator.

Customer: replied 4 months ago.
OK where is the starter located on my car?
Expert:  Marty replied 4 months ago.

Underneath the car on the passenger side bolted to the transmission bell housing.

Customer: replied 4 months ago.
What is a pyro fuse? And does that need to be replaced? Also is there an airbag module that needs to be reset?