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Current CLK 320 Cabriolet Former 1986 E 300D and 1959 190SL
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Discussion Starter #1
Lately, the driver's side seat belt extender in my 2004 CLK Cabriolet has been acting up. Sometimes it works properly but, often, when I close my door, the belt is not extended. If I open and close the door, it works. It doesn't seem to make a difference whether I insert the key before or after I close the door. Anyone know of a reset or something that might fix this?
 

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Premium Member
2004 CLK 240 Coupe
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11,377 Posts
Seems that none of us has any experience with this problem...:(

If the extender was totally non-functional, the WIS reports a known problem that concerns a counter, stored in the RVC control unit (Roll bar Vario roof Control)

Fault codes B1405 and B1505 signify faulty left/right seat belt extenders. This can be reset via STAR DIAGNOSTICS.

Your problem here could be caused by a faulty door contact switch. Sometimes working, sometimes not. Have you ever closed the door and seen the alarm message on the cluster?

The ignition switch is not the trigger to operate the extender, the door switch is. The ignition switch merely provides power to the associated control module.
 

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Current CLK 320 Cabriolet Former 1986 E 300D and 1959 190SL
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109 Posts
Discussion Starter #3
Thank you for your reply, Keyhole. There has been no warning message thus far. This seems to happen more often when I close the door first and then start the car. If I start the car and then close the door, it seems to work fine. It may well be the door contact switch or some sort of relay that isn't letting the control module actuate. By the way, what is the WIS? Thanks, Dave
 

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Premium Member
2004 CLK 240 Coupe
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11,377 Posts
By the way, what is the WIS? Thanks, Dave
It the German word for Workshop Manual. (Werkstattinformationsystem)

Sometimes for sale on eBay on 2 DVDs that you can load onto your PC. It covers most MB models from late 1980s to recently. (mine goes to 2005)

You folks in the US can get similar information from a subscription site. :thumbsup:
 

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Current CLK 320 Cabriolet Former 1986 E 300D and 1959 190SL
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109 Posts
Discussion Starter #5
My seat belt extender problem persists. When I turn on the ignition before closing either door, the extender works. If I close the door first, the extender does not work, but a muffled sound does come from the door pillar. Also, the seat belt warning does not come on if I drive off without fastening my belt. This must be related. Any ideas why?
 

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Premium Member
2004 CLK 240 Coupe
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11,377 Posts
This is a puzzler....:confused: Clearly the conditions for the SBE arm to operate are:

Door closed (from being open) AND ignition switch in posn 1 or 2.

The order of these events should not affect the operation. And if the seat belt is not fastened within 10 seconds, the SBE arm is withdrawn. There is a connection between the two situations, but it is complex.

The door contact switch (S17/3) is routed to N10/2 (rear SAM). The seat belt buckle switch (S68/3) goes to N2/7 (restraint system control module) They communicate via CAN B bus. In this situation, it is best to get your error codes read. They are provided to eliminate wild goose chases....
 

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1999 SL500, 2004 CLK500, 2006 Cadillac SRX
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873 Posts
My 1986 560SEC also had extenders that functioned similar to my 2004 CLK500 - I have noticed both to act quirkey, seemingly randomly.
 

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2004 clk55 amg
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270 Posts
Lately, the driver's side seat belt extender in my 2004 CLK Cabriolet has been acting up. Sometimes it works properly but, often, when I close my door, the belt is not extended. If I open and close the door, it works. It doesn't seem to make a difference whether I insert the key before or after I close the door. Anyone know of a reset or something that might fix this?
I've had this issue before...believe it or not, the voltage on my battery was too weak...so at start-up, occasionally, the seat belt would extend...but when the battery charge was too low, the seat belt would not extend. battery replaced...no more problems with seat belt...voltage indicator said that my battery was down to about 6 volts. do not take your car to your local dealership to get the battery replaced...you'll end up paying for the battery + labor. instead, call mercedes road side assistance and tell them to bring you a new battery...they will charge you for the battery, but labor for battery installation is free when you call roadside assistance. Hope this helps. good luck.
 
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