Can someone please tell me what resistance I should be getting from my 3 prong sensor when the engine is hot and when it is cold. I've been getting 60 ohms when it was cold, warmed the car up a little bit then got 82 ohms. Took it out for a good warm-up and when I returned got 60 ohms again. Now it seems to me that I should be getting some different readings. Of course I'm having some performance problems with the car as it seems to be running rich and I'm having some starting problems, answers? I'm pretty sure that the problem is narrowed down to this sensor...

from: (Table of voltage values of EZL/KE coolant Temperature sensor...)

Temp Celcius ---------Resistance KOhms
-20-------------------15.7
-10-------------------9.7
0---------------------5.9
10--------------------3.7
20--------------------2.5
30--------------------1.7
40--------------------1.18
50--------------------0.84
60--------------------0.60
70--------------------0.435
80--------------------0.325
90--------------------0.247

Looks like it's bad.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

Wrong sensor
3 prong sens is for aux fan and a/c cut out 105/115C switch...

Can somebody walk through exactly which sensor is which from front to back of M103 engine.

I have (from memory) a sensor with two vacuum pipes at the front, and electrical sensor with a single plug and two wires behind that and at the rear a sensor with two independant plugs.

I realise that sensor types change with year.

Thanks
Aussie 89 300CE

What I have is closest to the firewall is a 2 prong sensor, next is a 1 prong sensor and then approx. midway on the intake is the 3 prong sensor. I'm guessing that the 2 prong feeds my engine temp indicator on the instrument cluster, the 1 prong ???, but my mercedes parts guy is more or less (3rd party info thru my wife) confirming that the 3 prong feeds my computer info, can anybody back this up?

OK, fastlane indicates that the 2 prong feeds the CIS-E ignition system, can anyone confirm what the 3 prong and 1 prong do?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1D00YU6RY1DN1C0HZF&year=1987&make=MB&model=300-E-002&category=P&part=Water+Temperature+Sender

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1D00YU6RY1DN1CEJWY&year=1987&make=MB&model=300-E-002&category=G&part=Engine+Temp.+Sensor



http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1D00YU6RY1DN1C6DSF&year=1987&make=MB&model=300-E-002&category=C&part=Water+Temp.+Sensor&appEngines=_any

Single is temp gauge and 3 prong I already told you..
My schematics verify my info, so either your friend is wrong or Benz schematics are incorrect..

Got it, thanks for the info, reading off the 2 prong are way off what it look slike it should be as well, new part will be put in this week, Thanks to all that helped. I'll let you know the results.

One prong of the two-pronger feeds the ignition, the other prong feeds the CIS fuel injection. They're identical and interchangable. Each prong should register 1/2 the total resistance to ground. If both work, you'll get the total resistance between prongs. It's possible for one side to be open and the other to be working. If that's the case, the CIS should get the good side until you can replace it.

The single prong sensor feeds the dasboard temp. gauge. The threesome is fan contacts, as Arthur D. sez.

__________________
Norm in NJ
Next oil change at 230,000miles

What about the one at the front that has the two vacuum pipes plugged into it.

May be a non-US feature?

Do you have to remove anything to get to the 2-prong sensor? Is it immediately visible when you lift the hood? I think mine may be bad, so I'd like to test it. Thanks!
Mika