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 ShopForum > Technical Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 09-20-2010, 10:59 PM
Vice President of Snark
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 1,165
85 300TD: Three-prong plug near monovalve?

My '84 didn't have wiring routed up there around the monovalve.

Anyhow, I was cleaning up the engine bay on Puff this weekend and moved those wires out of the way to clear some debris. This round, 3-conductor connection literally falls apart in my hand. Tracing it down (roughly though a few harness junctions) I think it is for the A/C drier.

It's late and I don't have pics yet. Wanted to see if anyone knows what this is on description alone. I can plug it back together and the A/C still works, but it's no longer water tight. I guess I can wrap it in rubber tape, the kind that stretches and seals on itself. But is there a way to replace this connector?
__________________
'85 300TD "Puff The Magic Wagon" - On the road again!
'95 E300d - 110K Looking for a new home
'15 Volvo XC70 T6 - Wife's sled
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter
Reply With Quote
  #2  
Old 09-21-2010, 02:04 PM
Vice President of Snark
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 1,165
Here are the pics. Camera phone quality. But they get the point across.
Attached Thumbnails
85 300TD: Three-prong plug near monovalve?-three-prong1.jpg   85 300TD: Three-prong plug near monovalve?-three-prong2.jpg  
__________________
'85 300TD "Puff The Magic Wagon" - On the road again!
'95 E300d - 110K Looking for a new home
'15 Volvo XC70 T6 - Wife's sled
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter
Reply With Quote
  #3  
Old 09-21-2010, 07:42 PM
winmutt's Avatar
85 300D 4spd+tow+h4
 
Join Date: Apr 2006
Location: Atl Gawga
Posts: 9,322
Tach sensor I believe.
__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1987 300D Sturmmachine
1991 300D Nearly Perfect
1994 E320 Cabriolet
1995 E320 Touring
2001 Eurovan FOR SALE
1985 300D car, sold and missed.
OBK #42
Reply With Quote
  #4  
Old 09-21-2010, 08:16 PM
One step at a time
 
Join Date: Sep 2009
Location: Burleson, TX
Posts: 426
Hard to tell from the pics but because it is right next to the wheel speed sensor (coax wire, round plug) it looks to be the brake pad wear sensor.

This is not the location it is in in my SD, but it looks the same.
__________________
----Adam

1985 300SD 322,000
Reply With Quote
  #5  
Old 09-21-2010, 09:05 PM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
I believe the two above responses are incorrect and sorry, I don't know what it is either.

The tach gets it's signal from the transmission on an 85. The socket that used to house the tach amp is simply a cover for the diagnostic port that gets the signal via a magnetic pick-up on the front of the crank (Hall effect sensor).

It's not the wear pad sensor wire either, (a two prong plug) perhaps the item below it.

4the... if he has ABS, that may be the wheel speed sensor.
__________________
83 SD

84 CD
Reply With Quote
  #6  
Old 09-21-2010, 10:53 PM
Vice President of Snark
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 1,165
Quote:
Originally Posted by toomany MBZ View Post
The tach gets it's signal from the transmission on an 85. The socket that used to house the tach amp is simply a cover for the diagnostic port that gets the signal via a magnetic pick-up on the front of the crank (Hall effect sensor).

It's not the wear pad sensor wire either, (a two prong plug) perhaps the item below it.

4the... if he has ABS, that may be the wheel speed sensor.
Good to know that tach gets it's reading from the trans. Didn't know that. I guess my '84 did as well, because the diag port on the driver's fender looked the same.

Definitely not the brake pad sensor, I know those are the two-prong flat connectors. Speaking of which I need to install the new harnesses I pulled from Betty.

ABS I do not have. Something I'm interested in having one day. Maybe if I find that 230TE in Denver again...
__________________
'85 300TD "Puff The Magic Wagon" - On the road again!
'95 E300d - 110K Looking for a new home
'15 Volvo XC70 T6 - Wife's sled
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter
Reply With Quote
  #7  
Old 09-22-2010, 09:13 AM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
Yes, MB changed that (tach pick-up, tach instrument too) in 84.

The 85's have a few items older units don't.

I can't find anything on my car like that, or searching the epc.

Good luck, maybe with an electrical diagram you can figure it out.
__________________
83 SD

84 CD
Reply With Quote
  #8  
Old 09-22-2010, 09:23 AM
DeliveryValve's Avatar
Chairman of my Benz
 
Join Date: Jun 2006
Location: Central California
Posts: 4,044



The 3 prong round plug (top) is for the Rack Position Sensor located on the Injection Pump. The bottom prong rectangle plug (bottom) is for the RPM sensor, as noted by toomany, the sensor is located on the bellhousing and gets the signal from the teeth of the flywheel.

Both plugs lead to the so called EGR computer.



.
__________________
1983 123.133 California
- GreaseCar Veg System


Reply With Quote
  #9  
Old 09-22-2010, 09:42 AM
winmutt's Avatar
85 300D 4spd+tow+h4
 
Join Date: Apr 2006
Location: Atl Gawga
Posts: 9,322
Ah yes thanks, rack sensor. I knew it was something 85 specific
__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1987 300D Sturmmachine
1991 300D Nearly Perfect
1994 E320 Cabriolet
1995 E320 Touring
2001 Eurovan FOR SALE
1985 300D car, sold and missed.
OBK #42
Reply With Quote
  #10  
Old 09-22-2010, 10:24 AM
Vice President of Snark
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 1,165
Sweet. Thanks guys. Once you guys clued me to what it was, I was able to find more info. Good visual confirmation here: http://www.peachparts.com/shopforum/diesel-discussion/185572-1985-federal-300d-tachometer-repair.html#post1481907

Looks like this is a lot more junk I need to remove for EGR delete. It was sooo much easier on the '84...
__________________
'85 300TD "Puff The Magic Wagon" - On the road again!
'95 E300d - 110K Looking for a new home
'15 Volvo XC70 T6 - Wife's sled
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter
Reply With Quote
  #11  
Old 09-22-2010, 11:02 AM
DeliveryValve's Avatar
Chairman of my Benz
 
Join Date: Jun 2006
Location: Central California
Posts: 4,044
Quote:
Originally Posted by andrewjtx View Post
Sweet. Thanks guys. Once you guys clued me to what it was, I was able to find more info. Good visual confirmation here: http://www.peachparts.com/shopforum/showthread.php?p=1481907

Looks like this is a lot more junk I need to remove for EGR delete. It was sooo much easier on the '84...
If you want to remove the EGR, follow this thread and remove the stuff "X" out in the picture here.

EGR Delete/Remove




.
__________________
1983 123.133 California
- GreaseCar Veg System


Reply With Quote
  #12  
Old 09-22-2010, 11:43 AM
Vice President of Snark
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 1,165
Yeah, I've seen your diag on that as well.

I've yet to perform a full inspection of the vacuum on this car. There's definitely been some modifications of it, as the switchover valve was bypassed and I know there is a fuel filter put in line. Maybe this weekend I'll get a few hours to go over it all.

Car shifts fairly well once warmed up and all vacuum consumers work accordingly. So I don't have any obvious problems. Just need to sort out what I'm working with. I'll test plugging those two connections you recommend and see how it does.

-Andrew
__________________
'85 300TD "Puff The Magic Wagon" - On the road again!
'95 E300d - 110K Looking for a new home
'15 Volvo XC70 T6 - Wife's sled
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter
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 11:21 AM.


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