Which sensor is which
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Joined: Sep 2019
Posts: 83
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From: Reno, NV
Which sensor is which
hi there guys and gals, I hope you have a great day no matter where you might be.
I got a bit of a sticky problem here and I'm hoping someone can help me decipher it. I'm having trouble finding certain sending units or sensors. Yes I do have a FSM, but I cant find the info I need.
I have a 1986 C4, everybody knows that it's like 36 years old and I've been slowly and methodically replacing sensors and parts just because of the fact that there ancient.
So, recently I purchased a scan tool from 1320 and one of the things it indicated was that my coolant temperature was about 30° difference (cooler) then what was showing on the digital gauge.
So, I thought well the sending unit for the digital gauge must be at least 36 years old why not replace it. Went to my O'Reilly store picked up a new one and took the old one out and replaced it. After I did this things started to get screwy.
Before the sensor replacement my fans or I should say fan, would come on at about 212 to 218°. Now since I replaced the sending unit, and by the way this is on the right side of the engine between cylinders six and eight. Now the fan wont come on till almost 235. Unfortunately I broke the old sensor getting it out and I can't reuse it. Does this sound correct? Also I have been told that you can purchase a sensor or sending unit that will turn the fan on at approximately 180°. Since were starting to get hot here in Nevada it's time to get this straightened out. So my question is, is the sending unit on the right side of the engine between six and eight is that for the gauge? Or is there another sending unit located somewhere on the engine for the gauge and was the device I changed for the fan.
It's really difficult because I don't know what the previous owner did in regards to cooling system options he did live in Texas so I imagine there were some items that he did to help it stay cool.
I also went to the forum here looking to see if I could find some information on what sensors and sending units are aware. The guy at O'Reilly's (he owned a 96 c4) said that the fan sending unit was the one I replaced on the right side and he said the one for the temperature gauge should have been on the left side of the engine between cylinders one and three. On my car there is nothing between cylinders one and three. The sender or sensor that's under the throttle body I changed out right after I bought the car because I was told it was very important to have that one functioning properly. The only thing I'm waiting on is a thermal imaging gun that I bought to test and see exactly what the temperatures are at the hoses as well as at the sending units. As I said my scan indicated I was probably about 30° of difference between what it was showing and what my digital gauge is showing.
I hope I'll explain this properly if pictures are needed I can certainly post those next time around but if someone has some knowledge on this I would sure appreciate it. As always I thank the forum for any help they supply and hope y'all have a great day
Tony
I got a bit of a sticky problem here and I'm hoping someone can help me decipher it. I'm having trouble finding certain sending units or sensors. Yes I do have a FSM, but I cant find the info I need.
I have a 1986 C4, everybody knows that it's like 36 years old and I've been slowly and methodically replacing sensors and parts just because of the fact that there ancient.
So, recently I purchased a scan tool from 1320 and one of the things it indicated was that my coolant temperature was about 30° difference (cooler) then what was showing on the digital gauge.
So, I thought well the sending unit for the digital gauge must be at least 36 years old why not replace it. Went to my O'Reilly store picked up a new one and took the old one out and replaced it. After I did this things started to get screwy.
Before the sensor replacement my fans or I should say fan, would come on at about 212 to 218°. Now since I replaced the sending unit, and by the way this is on the right side of the engine between cylinders six and eight. Now the fan wont come on till almost 235. Unfortunately I broke the old sensor getting it out and I can't reuse it. Does this sound correct? Also I have been told that you can purchase a sensor or sending unit that will turn the fan on at approximately 180°. Since were starting to get hot here in Nevada it's time to get this straightened out. So my question is, is the sending unit on the right side of the engine between six and eight is that for the gauge? Or is there another sending unit located somewhere on the engine for the gauge and was the device I changed for the fan.
It's really difficult because I don't know what the previous owner did in regards to cooling system options he did live in Texas so I imagine there were some items that he did to help it stay cool.
I also went to the forum here looking to see if I could find some information on what sensors and sending units are aware. The guy at O'Reilly's (he owned a 96 c4) said that the fan sending unit was the one I replaced on the right side and he said the one for the temperature gauge should have been on the left side of the engine between cylinders one and three. On my car there is nothing between cylinders one and three. The sender or sensor that's under the throttle body I changed out right after I bought the car because I was told it was very important to have that one functioning properly. The only thing I'm waiting on is a thermal imaging gun that I bought to test and see exactly what the temperatures are at the hoses as well as at the sending units. As I said my scan indicated I was probably about 30° of difference between what it was showing and what my digital gauge is showing.
I hope I'll explain this properly if pictures are needed I can certainly post those next time around but if someone has some knowledge on this I would sure appreciate it. As always I thank the forum for any help they supply and hope y'all have a great day
Tony
Safety Car
Joined: Aug 2002
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From: SANTA CRUZ CA
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
On my 84 the dash temp sender is between 1 and 3; and the fan sender is between 6 and 8. I believe they swapped them around on the 85 but I don’t know for sure. The CTS is screwed into the intake at the front. You said you have a FSM so how is the fan meant to be controlled? Is it from a sensor or is it from the ECM?
Le Mans Master
Joined: Aug 2017
Posts: 6,936
Likes: 1,487
From: New Jersey
On my 84 the dash temp sender is between 1 and 3; and the fan sender is between 6 and 8. I believe they swapped them around on the 85 but I don’t know for sure. The CTS is screwed into the intake at the front. You said you have a FSM so how is the fan meant to be controlled? Is it from a sensor or is it from the ECM?
235 for main fan on seems about right imo. My car the dash reads a couple degrees higher than the cts in the intake.
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Yeah my dash is 10 Deg C higher than my CTS I’ve been meaning to measure it with my IR temp probe to confirm which one is correct but I keep forgetting to do it.
Le Mans Master
Joined: Aug 2017
Posts: 6,936
Likes: 1,487
From: New Jersey
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Yep mines been replaced as well. Probably twice because in the box of bits that came with the car there was a second one (also the new type). I figure the guy that owner it before me was chasing some of that cars many problems and just throwing parts at it.
