Ron,

With regard to installing a new sensor I posted the procedure and precautions some time ago, but that post is probably no longer available through the search process. Unfortunately, I didn’t keep a copy and I don’t know whether it’s been archived anywhere. Beyond sinking the leads, using the correct temperature, solder and heatshrink tubing, I also recommended that you repack the sensor case with new heatsink grease. This will ensure more even heat transfer between the sensor and the outside world.

When the W124 was introduced and for some time thereafter, the sensor was located in the left-corner bumper absorber. This location always made more sense to me than behind the license plate. Seems to me that the center location would be more prone to false readings particularly in city traffic, due to proximity to the radiator and exhaust from the car in front. I have no idea why MB moved the sensor back to the license plate location (maybe their engineers know).

Looking forward to the results of your tests,
Barrie

OK, i tried the 3000 ohm trick and that worked! but its displaing tempatures of 78-79 degrees F. is this accurate enough? i did use 3 1000 ohm 5% tolerance resistors solidered in series to achieve this temp. is the tolarence affecting my reading or is it a faulty display?

__________________
Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

To anyone interested, I bought 6 of thermistors per Barrie’s recommendation. (The vendor had a minimum order requirement.) They have not arrived. Once they do, I will sell the remaining devices for cost plus shipping. I think I paid 3.76 per device. Don’t know what shipping is.

Let me know if interested.

…Tracy

Adam,
Your display unit appears to be perfectly fine - the readout is well within tolerance for 5% resistors. If you want to be sure, then use 1% resistors and take 3 measurements. You should be within 1 degree C using the following standard resistor values: 3000 ohms = 25C, 1000 ohms = 25C, 39000 ohms = -25C.

Glad to hear we're getting more of those outside temperature displays working again(at a reasonable cost)! Good luck,
Barrie

Anyone have the fastlane part # for the Farenheight outside temp Display?
The sensor is probably bad, but the display is definitely cracked and broken... probably from heat.
Thanks alot and wish me luck.. never had the guts to pull my merc's cluster before, Im going to fix that darn clock too!

Jason M.

With the knowledge gained from the posts on the temp. sensor I have decided to fix mine as well.

First I have one question.
Barrie, what does it meen to sink the thermistor leads with clips when soldering.

Thanks

Mladen

Mladen,

What Barry meant was that you should use clips to heat-sink the leads going to the resistor so that it would not be damaged by excess heat during soldering.

Best of luck

Jason M.

I purchased a couple of these resitors.

Do you unclip the sensor at the front license plate and splice one in, solder one in...

i can't seem to find specifics as i read through.

I read a steady 136 degrees fahrenheit right now.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

I learnt it the hard way to locate the temperature sensor, namely removing first the license plate then the middle part of the bumper only to realize that it had been much easier with one screw instead of 6 .
See pix below:




Hi,

as you can see in the 4 figures the sensor is enclosed in a metall tubing, which is attached to a metall plate. When the tubing comes to an end there is the plastic shield of the wire, I think, close to the license plate .

My question is: where do you splice the wire, and how do you remove the tip (the sensor) and replace it with the thermistor?
A pictorial instruction would be great.

btw, Lee or anyone else, if you have ordered more resistor/thermistor/sensor than you need, I'd glad to buy one from you. Let me know, Thanks!

__________________
1996 E320 since 1/16/08, 171K miles as of Feb 2011

---------------------------------------------------------
1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

i think i got a couple of them, let me check..

if i recall they killed me on the shipping, that's why i bought a couple...

i have to check my workshop.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

I picked up an instrument cluster from a 1989 420 SEL the other day and am thinking about using it in my 1983 300SD, in order to have an OAT temp gauge.

I would simply transfer over the SD instruments into the SEL cluster housing and use the temp display, which is a 4 wire part number 126 542 02 27.

1. Can I just hook up a thermistor (listed previously in this thread) to the display, and then ground and 12 volts, or are there more components in the system than just the thermistor and the display?

2. Where do the wires go? (I have the harness that goes into the four wire plug)

• two browns (I assume these go to ground)
• green
• gray/blue
• purple/black

there isn't any connector in the engine bay on my W201. the temp. cable goes thru the firewall without any break. is there a connection before it enters the cluster?