Headlights will never turn off, no keys, had to remove the battery
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Headlights will never turn off, no keys, had to remove the battery
I have a 2003 c230k coupe for the past 7 years and now my headlights won't turn off.
Ignition off, engine off, keys off and automatic lights off. Doors are closed too and the headlights will stay on forever. I had to temporally remove the battery because I couldn't find any solution. I even tried to remove the fuse 62 and 63 and no sucess. If I put the negative battery wire back, the headlight will turn on just like that.
Can anyone help me? I can't find the anwser anywhere on google or here.
Ignition off, engine off, keys off and automatic lights off. Doors are closed too and the headlights will stay on forever. I had to temporally remove the battery because I couldn't find any solution. I even tried to remove the fuse 62 and 63 and no sucess. If I put the negative battery wire back, the headlight will turn on just like that.
Can anyone help me? I can't find the anwser anywhere on google or here.
Last edited by Jackson Xci; Dec 6, 2014 at 08:23 PM.
MBWorld Fanatic!
Joined: Jan 2005
Posts: 2,848
Likes: 15
From: Orange County
2005 C Wagon (No snickering please!)
The car scans all the switches on the canBus and issues output commands based on that information.
The headlight switch is scanned and if headlights are called for, a signal on the canBUS instructs the front SAM to turn on the lights. This is done by turning on a transistor. The transistor is integrated with a resistor to measure current flow for the "lamp out" message, and prevent excessive current flow. This all electronic system has no need for fuses.
The usual failure mode is shorted transistors causing the lamps to always be illuminated. The fix is to replace the front SAM.
There is a very small chance the headlight switch is bad, so even if turned off, it is still telling the car it is on.
Even more rare is the possibility of moisture in the front SAM causing it to misbehave. Remove the cover and let it dry might help.
The headlight switch is scanned and if headlights are called for, a signal on the canBUS instructs the front SAM to turn on the lights. This is done by turning on a transistor. The transistor is integrated with a resistor to measure current flow for the "lamp out" message, and prevent excessive current flow. This all electronic system has no need for fuses.
The usual failure mode is shorted transistors causing the lamps to always be illuminated. The fix is to replace the front SAM.
There is a very small chance the headlight switch is bad, so even if turned off, it is still telling the car it is on.
Even more rare is the possibility of moisture in the front SAM causing it to misbehave. Remove the cover and let it dry might help.
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,266
Likes: 170
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
Good to know!
The car scans all the switches on the canBus and issues output commands based on that information.
The headlight switch is scanned and if headlights are called for, a signal on the canBUS instructs the front SAM to turn on the lights. This is done by turning on a transistor. The transistor is integrated with a resistor to measure current flow for the "lamp out" message, and prevent excessive current flow. This all electronic system has no need for fuses.
The usual failure mode is shorted transistors causing the lamps to always be illuminated. The fix is to replace the front SAM.
There is a very small chance the headlight switch is bad, so even if turned off, it is still telling the car it is on.
Even more rare is the possibility of moisture in the front SAM causing it to misbehave. Remove the cover and let it dry might help.
The headlight switch is scanned and if headlights are called for, a signal on the canBUS instructs the front SAM to turn on the lights. This is done by turning on a transistor. The transistor is integrated with a resistor to measure current flow for the "lamp out" message, and prevent excessive current flow. This all electronic system has no need for fuses.
The usual failure mode is shorted transistors causing the lamps to always be illuminated. The fix is to replace the front SAM.
There is a very small chance the headlight switch is bad, so even if turned off, it is still telling the car it is on.
Even more rare is the possibility of moisture in the front SAM causing it to misbehave. Remove the cover and let it dry might help.
Junior Member
Joined: Jun 2013
Posts: 26
Likes: 1
c230
https://mbworld.org/forums/c-class-w...le-repair.html
My 2006 C230 had the same problem and solved later.
There are six same transistors BTS6133D and one of them shorted leading the light always on. You can easily find it out using a meter. I can't remember which one. 6133D can be found on Ebay for $1 or so.
I parted off the front sam by saw and reassembled by hot glue gun.
It is not hard to do so but save thousand of dollar.
My 2006 C230 had the same problem and solved later.
There are six same transistors BTS6133D and one of them shorted leading the light always on. You can easily find it out using a meter. I can't remember which one. 6133D can be found on Ebay for $1 or so.
I parted off the front sam by saw and reassembled by hot glue gun.
It is not hard to do so but save thousand of dollar.
