How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Pete Your Own Question
Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 28263
Experience:  Over 15 years experience as a Mercedes dealer technician
Type Your Mercedes Question Here...
Pete is online now
A new question is answered every 9 seconds

2003 C240 Mercedes. All functions worked on turn signal switch

Customer Question

2003 C240 Mercedes. All functions worked on turn signal switch but lever would not stay centered. Replaced switch and now no functions are working. Put back original switch but prob remains. No blown fuses found in all 3 fuse panel locations.
Submitted: 5 years ago.
Category: Mercedes
Expert:  Pete replied 5 years ago.
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.


I just need a little more info to assist better.

Have you checked your turn signal switch electrical connection to make sure it isn't damaged from being un plugged and plugged back in as in some cases the pins can bend in the connection?

Let me know so we can continue,Thanks Pete!
Customer: replied 5 years ago.
Yes, the switch and harness connectors are good. Connectors were checked because the first new turn signal switch was wrong (for 2002) and would not index into the main harness.
Expert:  Pete replied 5 years ago.
Is there anything else electrical in the vehicle acting up or not working properly since the switch started acting up?
Customer: replied 5 years ago.
Only functions associated with turn signal switch (i.e. wipers, high/low beams etc.) are not working. They worked before replacing switch and now they don't even with the original switch reinstalled. Thought maybe a fuse blew but fuses are all OK. Did check for maybe a pin being pushed out of connector on main harness but connectors are OK.
Expert:  Pete replied 5 years ago.
I apologize for the delay.

Were all fuses in all fuse boxes checked and found o.k.?
Customer: replied 5 years ago.
Yes all fuses in all 3 locations are OK.
Expert:  Pete replied 5 years ago.
Have you traced the wiring down the column to see if it has come loose or shorted/stretched under the dash?
Customer: replied 5 years ago.
Yes. That was checked when this problem came up and during inspection of connectors.
Expert:  Pete replied 5 years ago.

This turn signal switch sends signals for turning left or right as well as the other signals it sends from this switch assembly to the electronic ignition switch.

The electronic ignition switch then sends these signals on to the control units to control the lighting.Since all of the fuses are good and the turn signal switch is good as well then there may be an internal fault in the electronic ignition switch that is causing this issue here.

This vehicle should have the fault codes checked in it in the computers to see if any codes are set as this will aid and in some cases can pin point the failure.

EIS faults are common and this may be the issue here with the wiring and fuses being o.k.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 5 years ago.
Are you saying it's a coincidence that the EIS failed during the replacement of turn signal switch because everything worked prior to replacing switch. And as I said before, the only functions that are not working are operated thru the turn signal switch. Could the clockspring have anything to do with this prob? I'm asking because that's the only other component that was handled during the replacement of the turn signal switch. I will checked for any stored faults as you requested and let you know what I find. Just to let you know, we are a repair shop with 50 years of automotive/heavy equip experience between 3 mechanics. Been trying to get the elec. schematics for this car to help in fixing prob.
Expert:  Pete replied 5 years ago.
Usually it isn't a coincidence that the EIS will fail at the same time but if the wiring was checked and the fuses are good as well as your connections it may be possible.

If the first switch was plugged in at all and shorted any component out as it was the incorrect switch then it may have shorted the EIS.

If you can check fault codes in the computers on this vehicle and let me know what codes are set I can try and further assist with this here.

Thanks Pete!
Customer: replied 5 years ago.
The battery was disconnected during switch replacement. I'll let you know re: fault codes. We work on alot of cars, we just don't get many MB's.
Expert:  Pete replied 5 years ago.
Sounds good.
Let me know what you come up with.

Thanks Pete!
Customer: replied 5 years ago.
Hey Pete, sorry took so long but we work on vehicles used at the airport and when they go down on the planes we have to respond. Heres the faults that were found:
Eng Mgmnt section: P2314, 2315, 2316 & P2600
Elec. Gear Select section: P2001
Airbag section: B1025 & 27
Elec. Stab Prog: C1029, 1210, 1035
Inst Pnl: none
Dr. Mod: none
Brake Sys: none
Airco: B15A8 & B1210
Emobilizer: B1001

Looked-up all codes and cleared faults. Steering wheel is off so codes for airbags etc will prob come-up again. Will see if any other codes return. Let me know what these codes mean relative to the prob with no turn signal lever functions working. Thanks.
Expert:  Pete replied 5 years ago.
From looking at these codes here none of them apply to the turn signal issue that I can see.I was hoping there were some fault codes to go by to try and assist better on this here.I will have to opt out and put this question back on th e list to see if any other experts can assist better.If they can they should be with you shortly.

Thanks Pete!