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300 SL
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Discussion Starter #1
:confused:Alright all u shadetree mechanics of SL's, my speedometer is off by 5mph and my cruise control works when it wants to which has been three times in 17 months. What's the most likely cure? Transmission modulator? I have an automatic 300SL FROM 92. ANY HELP WOULD BE APPRECIATED.
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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11,122 Posts
Unmatched set of tire/wheels would cause Cruise control problem, but that is not your case. I would look into the wheel speed sensor.
 

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1991 300sl
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I had the same trouble with my 1991 300sl cruise controll and had read where you could resolder the connections in the cruise controll module/board to fix the problem. The module is under a cover under the hood on the passenger side. So I broke the tabes on the case,( didn't have screw driver to remove the case) unplugged the cable and pulled the circuit board out. Resoldered all the connections I felt safe in doing without destroying the board , put it back in and it works like a new one. Dn't know what connection cleared the trouble. I put the board back in a nd used a sealer around the edge of the board to make sure it didn't come out and was sealed form any water intering it. I als have a speedometer that reads 10mph fast. trying to find out why.
 

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"NEW OWNER" of a 1991 SL 500 weekend toy. Hope I don't go broke maintaining it!
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600 Posts
Cruise Control

I had the same trouble with my 1991 300sl cruise controll and had read where you could resolder the connections in the cruise controll module/board to fix the problem. The module is under a cover under the hood on the passenger side. So I broke the tabes on the case,( didn't have screw driver to remove the case) unplugged the cable and pulled the circuit board out. Resoldered all the connections I felt safe in doing without destroying the board , put it back in and it works like a new one. Dn't know what connection cleared the trouble. I put the board back in a nd used a sealer around the edge of the board to make sure it didn't come out and was sealed form any water intering it. I als have a speedometer that reads 10mph fast. trying to find out why.
Hi jmann00 - Could you confirm the module you're talking about is the one I'm pointing to in the attcahed photo? My CC does not work (sometimes jerks in and out) and if that's' the case I'll jump in there to look around.
I attached a picture to make sure I'm opening the right compartment you are referring to.
 

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1991 300sl
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Hope you got my message, yes that is where the cruise control amp/board is located. It is against the fender, held in by two screws that are very hard to remove. that's why I broke the tabs on the cruise control case to remove the board. You can then put it back with some sealer to hold it in. You don't need to add any solder, just heat and melt the existing solder. you should only have to do the large connections. good luck.
 

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"NEW OWNER" of a 1991 SL 500 weekend toy. Hope I don't go broke maintaining it!
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600 Posts
thanks jmann - I did not get any other message however. Not sure if you emailed?
 
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