GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Need help to connect Cu 0650a to start 2012 GL550

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Old Jul 4, 2021 | 11:27 AM
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2012 GL 550
Need help to connect Cu 0650a to start 2012 GL550


Need to know where to enter this one.

Same request: need to know where this portion should go so car can start.

My 2012 GL550 was not starting sometimes. Key was not doing anything. A while ago there was a water leakage issue.
Dealer did not know and he said just change the whole key inside portion which will cost around $1500. I declined and started myself investigating.
it was starting fine when it was cold weather or I stop the car and left it off for 3-4 hours. My guess was an inside cable connected to key was also got wet and can not turn on if it is Hot. After turning off, takes few hours to cold down and then first click starts. Before that wait time nothing happens, no sound and no click at all.
Needed help to start my GL550. The key was not doing anything. So I opened under the driver key portion and while checking/pushing all keys, by mistake, I unplugged a cable which has long pin which says CU0650a. See pic. Need help to find where to plug that back in. And then see if atleast it starts like before (after couple hours cooling down)

I tried watching many videos, but so far not found any which shows that kind of long pin/key(not sure what is the name)
Need help to atleast connect it back.
thanks in advance.
Attached Thumbnails Need help to connect Cu 0650a to start 2012 GL550-cf54f451-cf97-4b59-869b-e8ea6744f164.jpeg  
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Old Jul 4, 2021 | 11:42 AM
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2003 CL 600
Those are vent temperature sensors, should have nothing to do with starting? It will go into one of the black plastic air ducts in the area you're working, you should see a small hole. It just sits in the air stream to provide temperature feedback to the HVAC module.

I'm not sure I follow what you've done to fix the car here. The ignition switch failures are fairly common on that platform, there is a write-up here about re-soldering the points that fail inside the switch. It's often temperature related as yours is. I've seen water damaged CAN bus bars in those trucks, check the kick panels on both sides, if they got wet and corroded they are cheap to replace and will cause the same issue, resistance increased due to corrosion and then even more by temperature to the point where they break the circuit until it cools.
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Old Jul 4, 2021 | 11:50 AM
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2012 GL 550
Thank you very much for the quickest response with all the details. I am going to start that today and update you.
happy July 4th and take care.
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