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2007 S550
105 Posts
Discussion Starter · #1 ·
I have an SOS switch that failed(overhead console). It's a system that is no longer in use so I don't care too much about repairing it. I have somebody that is going to code it out sometime next week to nip it in the bud but I thought I'd mess with it until then.

Here are the symptoms... I get an SOS Tele Aid Inop notification on the instrument console intermittently. I can clear it with OK but it comes back after 1-3 minutes. The fault code tells me that it's the SOS pushbutton. Testing for open and closed actuation through DAS shows no resistance so it's an open circuit. I did a manual test of resistance between pin 1 and pin 3 on the switch and got nothing. It should read between 700-1300 ohms when it's in no-load position.

I popped a 1k resistor between pin 1 and pin 3 at the harness and now I get the SOS Inop notification just one time at startup instead of every 1-3 minutes. That's an improvement! I've cleared the fault codes but it came back at the next startup. Any idea of what the system tested resistance for the open SOS switch at startup should be? A new switch is unavailable and a junkyard overhead console in Savanna Cashmere(brown) is $250. Not going there!
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