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Anybody have the resistance vs temperature curve for the sensor that runs the temperature gauge? I've searched on here and on google, and can't find one. Need to diagnose a low running temperature issue (running about 70 C these days, thermostat replaced last year to address a reading 5 deg higher than that, but didn't).

Trying to see if the gauge is reading properly for the resistance I measured. If it is, I'm gonna try a new sensor, since I don't think that 3 different thermostats could be the issue (original when purchased in 2003, another that Jonathan put in last year). If the gauge isn't reading properly, I'll likely ignore it if I can determine the engine running temperature is above 80.
 

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Anybody have the resistance vs temperature curve for the sensor that runs the temperature gauge? I've searched on here and on google, and can't find one. Need to diagnose a low running temperature issue (running about 70 C these days, thermostat replaced last year to address a reading 5 deg higher than that, but didn't).

Trying to see if the gauge is reading properly for the resistance I measured. If it is, I'm gonna try a new sensor, since I don't think that 3 different thermostats could be the issue (original when purchased in 2003, another that Jonathan put in last year). If the gauge isn't reading properly, I'll likely ignore it if I can determine the engine running temperature is above 80.
I know the curve for the 4 pin is in the manual as I have used that. I will take a look. Or you can, if you downloaded it. It's just a matter of finding the correct dang page.


Dan
 

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This isn't the 4 pin, one single wire connection.
I understand, I was just saying there is a Curve for the 4 pin as in, there are ohm/temp curves in the online manual for at least for the 4 pin sensor. I also think I checked the Gauge sensor with a chart as well.

I just looked and looked and can't find the page again. Damn index system. I have to leave now, won't be back until much later. Browse the on line manual and see if you can find it.

Dan
 

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Well, I give up. I found the 4 pin graph in the Engine Electrical/ distributor section. I found ohms for the low coolant sensor in the cooling section but other than the actual schematic and part number designator of B13, I can't find a ohm chart for it.

If you can't find it, I will stick a meter on mine as it warms up, so let me know if you need this.

Dan
 

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Discussion Starter #6
Well, I give up. I found the 4 pin graph in the Engine Electrical/ distributor section. I found ohms for the low coolant sensor in the cooling section but other than the actual schematic and part number designator of B13, I can't find a ohm chart for it.

If you can't find it, I will stick a meter on mine as it warms up, so let me know if you need this.

Dan
That would be welcome . . . What is your indicated running temperature? I measured 69.5 ohms, then read right at 80 deg C (car not running) when I plugged it back in.

Oh, and I found the same graph you did, but it isn't for this sensor. Google and Yahoo have turned nothing up as well.
 

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Hattenator

What section did you find that one in? I don't think that one will help him but might still be useful. I don't recall if this sensor increases or decreases to work the gage, but this test keeps saying if 0 is is Ok. It has to change in resistance to work the gage.

I will run a oHm meter on mine in the AM and note increasing temp/resistance reading.

You know what we should do. We should get a Club together, mmmm one East Coast one West Coast ( one unit might work ) and buy a Lambra test unit which once we learn how to use the damn thing would make all this trouble shooting much easier. It plugs into the test port. Club members could just send it to who ever needs it next. Or rent it out. The Test Unit Part # is in the manual but I couldn't find where to get it online.

Dan
 

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For some reason it I uploaded the same page twice I think this is what you are looking for and what I should have posted earlier. I made a large versioon of the ohm to temp graph it will be at the bottom of the page.


 

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Dan

A quick way to find things in the manual is to

1. open Adobe
2. Click on edit then go down to search
3. A screen will come up on the right hand side with a search box depending on the version of adobe reader you have.
4. Click on search all PDF Documents in
5. Then on click on the dropdown box below that and locate your PDF folder in the W201 Manual after you have located it once Adobe will keep it there
6. Type your text you want to search for in the box above.
7. then click search

Reference screen shot at the bottom of the page. doing searches like this makes it much easier to locate what you want to find in the manual.

As a test search type in testing coolant temperature sensor

It should find 3 folders Locate on 50006 pdf when you click on that link in adobe it should open up the pages I have attached.

you can be as specific as you like or very general when searching in Adobe. Once you locate a document that you think is the correct, make sure you always confirm that it is for the year and engine type of 190 the question is about. As you will see in the test search there was 3 files for testing the sensor. One covers the 16V engines one covers gas engines and the last covers Diesels.

I hope this helps you in finding things much easier in the manual when you can't find them by just looking it the normal index

Jim
 

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That would be welcome . . . What is your indicated running temperature? I measured 69.5 ohms, then read right at 80 deg C (car not running) when I plugged it back in.

Oh, and I found the same graph you did, but it isn't for this sensor. Google and Yahoo have turned nothing up as well.
Well, I sort of messed up, my neighbors are moving and I got sidetracked talking for a bit so I didn't get the initial warm up very good.

My 92 2.3, gage is operated by the Single pin on the 3 pin sensor on top of the Head near the thermostat housing.

I should have put my meter on 200 ohms to get the decimals, sorry. Now I had to pull the connector each time, read the gauge, pull the connector, take a reading and run back to see the gage. Talking messed me up between 40c and the first mark.

It appears your 69.5 and my 70 at 80c would agree as we are just eyeballing the gage when we think the gage is on the line.

40c 109
70c 90
80c 70
82c 61
85c 57
90c 52 Outdoor temp is 54 F, 90 was as hot as she would go just idling.

Dan
 

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Dan

A quick way to find things in the manual is to

1. open Adobe
2. Click on edit then go down to search
3. A screen will come up on the right hand side with a search box depending on the version of adobe reader you have.

Had a chance to check out the New and Improved Search Engine. Works pretty well, just like Google, depends on what you ask to look for.

Many Tks
Dan
 

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Discussion Starter #15
Well, I sort of messed up, my neighbors are moving and I got sidetracked talking for a bit so I didn't get the initial warm up very good.

My 92 2.3, gage is operated by the Single pin on the 3 pin sensor on top of the Head near the thermostat housing.

I should have put my meter on 200 ohms to get the decimals, sorry. Now I had to pull the connector each time, read the gauge, pull the connector, take a reading and run back to see the gage. Talking messed me up between 40c and the first mark.

It appears your 69.5 and my 70 at 80c would agree as we are just eyeballing the gage when we think the gage is on the line.

40c 109
70c 90
80c 70
82c 61
85c 57
90c 52 Outdoor temp is 54 F, 90 was as hot as she would go just idling.

Dan
That is certainly in line, many thanks. My gauge is run by a single pin sensor that is in the head (I think) just above the throttle cable and linkages. What this tells me is that the gauge is reading properly for the resistance it is presented. I'll acquire another sensor, pop it in and see if it changes the reading (of course, that would mean I've put in 2 thermostats for nothing).
 

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Hi.

I measured my CTS resistance in 2 ways:

1) multimeter lead on one prong and another lead to engine ground ( got readings 358 ohms @ 80 degrees Celsius and other prong 329 ohms.)

2) one multimeter lead on one prong and other lead on other prong (got resistance reading 687 ohms)

Which way is the correct way to measure resistance of CTS ?
 
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