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 > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-01-2004, 04:10 PM
dieselmania's Avatar
Registered User
 
Join Date: Jul 2003
Location: Tucson, Arizona, USA
Posts: 552
engine speed sensor (long)

I usually post on the diesel forum but I am having what I believe to be engine speed sensor problems on my 87 300D so I thought I'd post on this tech forum. What seems to be happening is when the underside of the car gets wet, the air conditioning compressor quits and the tachometer also quits. They won't work again till everything dries out, maybe 45 min to 1 hr. Even shutting down and restarting won't bring them back up.
I have read briefly about the Klima relay, but I am suspecting the engine speed sensor because I can't really see the Kima getting wet where it is located.
My question is, does the engine speed sensor also send the signal to the tach? Or vice versa? I am thinking if there is a failure in the speed sensing circuit that there would be no signal for the compressor sensor to compare, keeping the compressor circuit open.
Also, how exactly do I get at the engine speed sensor? Is it underneath the car?
Is there another sensor or relay I should be looking at, given the facts? I think that the fact that the tach and the compressor both go out at the same time would be a pretty good clue for someone more experienced in this system than myself and I would sure appreciate any help.
By the way, I also considered that when the car gets wet the belt probably slips which could also probably trigger the sensors to cut power to the A/C from the difference in compressor vs engine speed, but if this were the case, wouldn't the cutout reset after shutting down, rather than having to wait 45 min to 1 hr? And why would the tach also fail?
Thank's in advance for any and all help.......Brian in HOT Arizona.
__________________
Brian
87 300Dturbo 160K #14 head still running R-12
02 F350 Powerstroke 170K
05 Chevy Express 1 ton w/Royal Utility box 100K
08 Infiniti FX-35 39K
Reply With Quote
  #2  
Old 08-01-2004, 04:27 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
The crank sensor is located on the bellhousing and reads the flywheel. The signal is carried by the circuit to the EGR transducer which converts the inducted AC signal into a pulsed DC signal. That engine speed signal is then used by all that need it, including the AC, the idle stabilization system, the tach and probably the ABS.

The OVP powers the EGR transducer if I recall and thus can kill the signal.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #3  
Old 08-02-2004, 12:13 AM
dieselmania's Avatar
Registered User
 
Join Date: Jul 2003
Location: Tucson, Arizona, USA
Posts: 552
Thanks Steve I'll just have to test the sensors and relays as per the manual. Trouble is, it's not so easy when it is intermittent. I guess first I should look to see what can get wet.
__________________
Brian
87 300Dturbo 160K #14 head still running R-12
02 F350 Powerstroke 170K
05 Chevy Express 1 ton w/Royal Utility box 100K
08 Infiniti FX-35 39K
Reply With Quote
Reply

Bookmarks

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 04:15 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, 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