Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Mercedes-Benz SL Discussion Forum

LinkBack Thread Tools Display Modes
Old 09-25-2007, 09:59 PM
Registered User
Join Date: Sep 2007
Posts: 13
'85 380sl idle speed problem

'85 380sl, 75K miles, generally extremely reliable and runs very well.

During last couple of months idle speed had occasionally gone to 15k then returned to normal 6-8k. Now stays at 15k +
Cleaned idle control valve with WD 40. Get function ( can hear click and see rotation of internal motor) on bench by applying 12v dc. When installed the idle speed is still at 15k. Only seem to get 6+/- v dc from plug powering the unit. ( Also tried second control valve from local junk yard - assumed probability of two bad ones low?) Idle speed does not come down with either control unit. If I power the unit with full 12v dc, engine stops.
Assume problem either valve or electronic control. Am I correct ? Anybody with similar problem and saved by something else ?
And where is that electronic speed control box hidden ?
Help !
Reply With Quote
Old 09-25-2007, 10:14 PM
Registered User
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 4

There is an Idle speed control unit behihd the glove box. It may be your problem.

Reply With Quote
Old 09-26-2007, 09:35 AM
Registered User
Join Date: Mar 2003
Location: Convent Station, NJ
Posts: 755
I also have an 85 380SL. I finally swapped out the Idle Control Unit with a known working piece and it solved my problem. Beware of Used Ebay units if not guaranteed. I was lucky enough to find a member here who had a working unit.

Below is a pic of it's location behind the glove box. Note that I had to pull the rubber vacuum tubes off the actuators (pink) in order to gain access.
Attached Thumbnails
'85 380sl idle speed problem-idle-control-valve.jpg  

'85 380 SL (sold)
'85 Carrera Flatnose
'71 280 SL Signal Red/Cognac
Reply With Quote
Old 09-26-2007, 11:45 PM
Registered User
Join Date: Sep 2007
Posts: 13
Thanks very much. That was great and speedy help. Will pull the glove box liner and try a replacement control unit.
Reply With Quote
Old 09-28-2007, 11:01 AM
Registered User
Join Date: Sep 2007
Posts: 13
thanks again problem solved.

Many thanks. Especially useful was the picture of the circus behind the glove box. found matching idle control in local yunk yard, plugged it in and idle went back to normal. Also learned that WD40 does a good job removing some of the carbon in the idle control valve.
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 05:31 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page