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1989 560SL 60000 miles From California Location Vancouver
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5 Posts
Discussion Starter #1
Hey I’m new here but I have an issue with my grandfathers 1989 560 sl with 60k miles. It sat for 5 months in a storage locker and my father and I took it out and it drove fine. A week later we noticed it was idling at 1500 rpm we were worried so we checked under the hood nothing noticeable and we went home and did some research my best guess is that the Over voltage protection relay needs to be replaced which I bought off ebay and arrives tomorrow. I also jumpstarted the car and inverted the plugs and steam/smoke came out of the battery if that means anything. If anyone could help that would be great.
 

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1987 560 SL, 1990 300E 4Matic
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435 Posts
You may want to check that the small wire which attaches to the positive side of the battery along with the main cable is firmly attached. That wire supplies power directly to the idle control computer. A detached, loose, or bad connection will result in a high idle. This happened to me once. You may also want to check the throttle (etc.) linkages to be sure that nothing is hanging up.
 

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2013 SL550 Grey/ Red/Black Ash wood with every option
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417 Posts
Stephan, I'm not sure what this statement means. "I also jumpstarted the car and inverted the plugs and steam/smoke came out of the battery". Do you mean you hooked the jumper cables onto the wrong terminals??? As far as the high idle goes, do what benztag said, check all throttle linkage. More than likely it's your Idle Control Valve. See the attached pic for reference. You might be able to take it off and clean the inside with some carb cleaner.

Thor
 

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1983 380 SL
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2,444 Posts
My first guess wouldn't be the idle control valve although it's a good thought. The over volt protect relay would be my first suspect. There is a fuse on top of the relay that can blow and if it blows it will give you a high idle. bTw... real easy to check the idle control valve... with the ignition on, disconnect to two prong connector on the idle control valve and then while listening carefully move the connector on and off the pins. Basically your repeatedly plugging the connector on and off. If you hear a clicking coming from the valve as you plug the connector on and off, the idle control air valve is probably doing what it should. It's not definite, but a pretty good indication.

Good luck.
 

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1989 560SL 60000 miles From California Location Vancouver
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5 Posts
Discussion Starter #6
Thanks everyone the fuse in the ovp was blown replaced it and runs fine now to replace the speakers!
 
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