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 03-16-1999, 07:38 PM
donwo
Guest
 
Posts: n/a
The temp gage on my 87 300e constantly reads higher than the actual outside temp by 10 degrees or so. Is this normal? Where is the sensor locacted and is it easy to replace?
Thanks I


Reply With Quote
  #2  
Old 03-16-1999, 08:48 PM
M.B.DOC
Guest
 
Posts: n/a
THE TEMP. SENSOR IS POSITIONED ON THE
FRONT BUMPER JUST BEHIND THE LICENSE PLATE
MOUNTING BRACKET. IF THE SENSOR HAS BEEN DAMAGED OR MOVED TO ANOTHER LOCATION IT COULD ACCOUNT FOR ERROR IN CALIBRATION.
Reply With Quote
  #3  
Old 03-17-1999, 12:56 AM
Benzmac
Guest
 
Posts: n/a
I have seen the sensor misplaced usually towards the radiator(a hot area) cause this problem.
Reply With Quote
  #4  
Old 03-17-1999, 08:09 PM
Ken
Guest
 
Posts: n/a
The temperature indication is very sensitive to sunlight shining on your license plate, especially when sitting (the airstream usually cools the license plate quickly after you start driving), but if you drive into the sun (and depending where you live -- e.g., Florida, Arizona?) your sensor may read higher than a properly shaded meteorological thermometer (viz., your radio's weather reports).
On the other hand, your temperature sensor may be damaged or defective and need replacement.
Reply With Quote
  #5  
Old 08-01-1999, 01:13 AM
Robert W. Roe's Avatar
Registered User
 
Join Date: May 1999
Location: Lehigh Valley PA
Posts: 1,330
May I ask how and exactly where this sensor should be mounted? I just got an '84 300SD and the silver-gray wire was hanging down below the license plate. I pushed it back behind the bumper but I want to mount it properly to avoid damage.

------------------
Robert W. Roe
1984 300SD 164K miles

Reply With Quote
  #6  
Old 08-01-1999, 09:38 PM
Registered User
 
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
It is usually connected to the rear of the front tag.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM


Reply With Quote
  #7  
Old 08-21-1999, 06:50 PM
Registered User
 
Join Date: Aug 1999
Posts: 6
The temperature gauge on my 1987 300D is not working at all - no LCD. How do I replace this?
Reply With Quote
  #8  
Old 08-21-1999, 08:13 PM
rego
Guest
 
Posts: n/a
Mine is not working either. 86 300E The dealer wants $240 for the part in the dash. That is a little steep. It looks like my LCD was over heated or bent. Larry
Reply With Quote
  #9  
Old 08-21-1999, 10:03 PM
Moderator
 
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
With M. Benz pushing harder & harder for their major parts vendors (VDO in this case) not to do business with the aftermarket prices will rise higher!! Just as with your outside temp gauge. If you had a new car w /digital dash then the complete instrument cluster would need replacing.

------------------
MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. TECH
190E 2.3 ITS RACECAR


Reply With Quote
  #10  
Old 11-01-1999, 09:01 PM
Barrie
Guest
 
Posts: n/a
If your outside temperature gauge is not working the fault is most likely with the sensor unit. You can test both the sensor and display by connecting a 3,000 ohm resistor in place of the sensor. If the display is working properly then your gauge (with power on) will give a readout of approx. 77 degrees F (or 25C if you have a celsius gauge).
Having verified that the fault is with the sensor, you need only replace the sensor thermistor (about $5). However, M-B sells only the complete cable assembly (the sensor at the end of a long piece of wire, for about $50), which requires about 2 hours to route - hence the $200 cost. To minimize this labor some mechanics will buy the assembly, cut off the end, and splice it into the old cable. Spliced connections, particularly in the engine compartment, are not a good idea! Instead, you can easily replace the sensor yourself for $5 with no splices. Use a negative temperature coefficient (NTC) thermistor of 3k at 25C, such as Fenwal #192-302LET-A01 or Thermometrics #EC95F302W. They are readily available from any electronics supply house.
If you require more detailed procedures on testing or installation, post your questions and I'd be glad to oblige.
Reply With Quote
  #11  
Old 11-01-1999, 09:31 PM
Registered User
 
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Barrie, this is one good bit of info. Will you register? I want strong mechanical minds on this site!
Thanks again.

------------------
Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM


Reply With Quote
  #12  
Old 01-01-2000, 04:17 PM
tsuru
Guest
 
Posts: n/a
Where is the other end of the lead running from the sensor? (Still waiting for my W124 CD). I want to test the system with the 3000 ohm resistor without trashing the sensor.
Reply With Quote
  #13  
Old 01-01-2000, 05:34 PM
Barrie
Guest
 
Posts: n/a
You have a number of options.
1)You can test the temp display part of the system by connecting the resistor to the input connector in the rear of the instrument cluster. If you get a good reading then the fault is either the sensor or the ground connection.
However, this test requires removal of the instrument cluster which is not a trivial task.
2)The sensor is much easier to get at, and most likely the problem; if not, its days are numbered anyway. There's no need to "trash" the sensor; just desolder one end of the sensor and clip the resistor across the two wires. At worst you'll destroy a $2 part if you screw up.
But it's your call. Let me know how you decide to approach it.
Reply With Quote
  #14  
Old 01-02-2000, 06:53 PM
tsuru
Guest
 
Posts: n/a
Isn't there a terminal block somewhere you can get to? MB ran the leads all the way from the sensor to the inst. cluster?

The guage always reads 136F. This would indicate no resistance, correct?

[This message has been edited by tsuru (edited 01-02-2000).]
Reply With Quote
  #15  
Old 01-02-2000, 10:01 PM
Barrie
Guest
 
Posts: n/a
Normally it's a straight shot, but you can verify that by tracing the wire from the sensor through the left-side harness to the instrument cluster.

The sensor is an NTC (negative temperature coefficient) thermistor. Consequently, your excessively high reading means that the thermistor's resistance is lower than it should be.

You can be quite confident that the sensor is bad -- and it's very simple to replace. In trying to be helpful, sometimes our descriptions make the job sound more onerous than it really is.


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


Similar Threads
Thread Thread Starter Forum Replies Last Post
300e Door Panels....All 4 Tan and Front Blue FS!! 6cndmbz Mercedes-Benz Used Parts For Sale & Wanted 0 06-13-2004 01:32 AM
two temp sending units? 617 turbo coachgeo Diesel Discussion 6 07-02-2003 11:07 PM
300e high idle all the time CadTech7 Tech Help 2 10-21-2002 03:59 PM
C280 A/C Temp. Question 767Flyer Tech Help 6 07-03-2002 05:58 PM
Low engine temp no heat razorman Tech Help 4 04-09-2002 05:59 PM



All times are GMT -4. The time now is 12:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page