Temperature Sensor

[Mexicano]

Do You know where is loacated the temperature sensor on a K4M engine?...my fan is not turning on since this morning, only when I turn on the A/C the fan works, other wise the temperature raises and the fan never goes in...need to know if there is a sensor that turns on and off the fan and where It is located.

Thanks!

 

[MicKPM]

Generally the cooling fan switch circuit is controlled by the ECU and has a single temp sender located in the thermostat housing on the gearbox side of the cylinder head.

A/C equipped cars are slightly more complicated though and there should be a surface temp resistor on the radiator frame itself which, when they fail, can cause this issue.

Ideally you need diagnostics to check the live data stream from the CTS to the ECU to firstly check it is sending a reading and that secondly, it is realistic. Then if all is good there you need the diagnostics to actuate the cooling circuit (this will be different to the A/C "low speed" circuit). If it doesn't work you know there's a circuit issue (be it wiring or a component) but as the fan works when you "request" A/C function we can safely rule out the fan/motor assembly itself.

Mick
Diamond Motors

 

[Mexicano]

Generally the cooling fan switch circuit is controlled by the ECU and has a single temp sender located in the thermostat housing on the gearbox side of the cylinder head.

A/C equipped cars are slightly more complicated though and there should be a surface temp resistor on the radiator frame itself which, when they fail, can cause this issue.

Ideally you need diagnostics to check the live data stream from the CTS to the ECU to firstly check it is sending a reading and that secondly, it is realistic. Then if all is good there you need the diagnostics to actuate the cooling circuit (this will be different to the A/C "low speed" circuit). If it doesn't work you know there's a circuit issue (be it wiring or a component) but as the fan works when you "request" A/C function we can safely rule out the fan/motor assembly itself.

Mick
Diamond Motors

Thanks for the input.

I guess the temp sensor is o.k. bacause I have reading on the dash....I was wondering if the sensor has two circuits: one for the dash gauge and one for the ECU temp signal input and this could be bad?....seems like this issue started after I installed a set of weber injectors for 2.0 Lts. Clio(250 c.c.), May this be related to the issue I have now?

Regards

 

[MicKPM]

The dash gauge isn't a fair test as its pretty inaccurate due to the ranges being quite wide. Ideally, as uts a simple two wire resistance based sensor, you will need to look at the Injection ECU live data and graph it (if your kit will allow it) to look for signs of a signal problem.

You have checked the connector to the high speed fan yeah? I know it may be stating the obvious but if any corrosion has gotten in it can also stop the cooling fan from working so worth a look.

 

[Mexicano]

The dash gauge isn't a fair test as its pretty inaccurate due to the ranges being quite wide. Ideally, as uts a simple two wire resistance based sensor, you will need to look at the Injection ECU live data and graph it (if your kit will allow it) to look for signs of a signal problem.

You have checked the connector to the high speed fan yeah? I know it may be stating the obvious but if any corrosion has gotten in it can also stop the cooling fan from working so worth a look.

Thanks again, which "program" and data cable would You recommend to check the live data?

 

[MicKPM]

I use CLIP but likely hood of you having access where you are is slim. I'd say try an ELM based interface 327 or better and then one of the many free pieces of EODBII software to see what the ECU is seeing.

 

[Mexicano]

I use CLIP but likely hood of you having access where you are is slim. I'd say try an ELM based interface 327 or better and then one of the many free pieces of EODBII software to see what the ECU is seeing.

Thanks!...I will get those tools ASAP....seems ike the CLIP is Renault specific tool and could be the best but my car was sold by Nissan and even is just like a Renault Symbol or Clio, my VIN is different...not sure if the CLIP is going to recognize it....What Do You think?

 

[Mexicano]

I got this one---hope It works...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120912488916&ssPageName=ADME:L:OU:MOTORS:3160

 

[Mexicano]

As the temp sensor is not expensive, I decide to give it a try and replace for a new one...voila!, it was bad...I installed the new sensor and the fan started just pass the middle ofthe temp gauge, just like before....

 

[octavio.zl]

Hi there! I see this thread is pretty recent, I am having almos same exact problem on a F4R (Clio 172). My temp gauge, when previously was sat exactly at the middle, now is at 1/4 and only when the car is not moving (so no airflow cooling the engine). I thought it was a thermostat issue, so I replaced it, problem is still there. Now, I found that the fan does not cut in unless I hit the A/C button. I still get a gauge reading.
I am thinking of either of three posibilities:
- the signal wiring from the temp sensor to the ECU is f*ed or corroded, so faulty signal coming from ECU to dashboard and also no signal sent to fan
- "A/C equipped cars are slightly more complicated though and there should be a surface temp resistor on the radiator frame itself which, when they fail, can cause this issue" Where is this sensor, I have never read about this, even in the manuals! does it also applies for phase 2 Clio 172?
- New thermostat is stuck maybe, causing the car not to reach normal temperature + wiring problem to the fan


Thanks guys...

 

[Mexicano]

Octavio:

If I understood, your problem seems to be "low temp reading" and fan never goes off?

I may look into the wiring from temp sensor to ECU and from ECU to the relay and "resistor" for the "two speed feature"...Maybe a wiring problem?

Did You try replacing the temp sensor as I did???

Regards

 

[octavio.zl]

Thanks for the response... the problem is sorted out, let me post further information to others:
The cooling system works as follows:
ECU has two inputs for starting the fan, one is temperature sensor (inputs 18 -gray cable- & 46 -violet
cable-) , the other is the A/C status (via CAN, so, no specific wire for this, CAN IS ON 57 & 27 FYI).
As well it has only two output signals for the Fan, output signal 11 low speed -pink cable- & 69 "high
speed" -orange-. each controls a relay.
On the relay box, there are 7 slots (one empty), there are three big ones and three little ones. I looked
some pictures and some boxes look different, so I will handle letters, relay "A" is for normal speed (in my
case is the big one to the very right on the "Big ones" row, receives ECU signal 69 -orange) and sends a
brown cable a termistor on the fan shroud. Relay "E" is for low speed (one little right to the empty slot),
it receives the signal from ECU 11 -pink- and sends to the termistor a gray one. From the termistor there is
a green going out, which is the only signal arriving to the fan the black is earth. Other boxes might be
different, my car is a phase 2 172 full fat lets say. so I am sure this could differ from some of your cars,
hopefully not much. We will check all this wiring & components without using OBD...

SOFTWARE
ECU starts the fan on LOW speed if (output signal 11 -> relay "E")
Coolant temperature >=100°C (sensor resistance around 170 ohm)
A/C is ON with mid~low blower speed (this I discovered by trial)
Two minutes after turning the engine off, the engine is hotter than 108°C (antipercolation system)
ECU will send HIGH speed signal if:
Coolant temperature reaches 105°C (sensor resistance around 140 ohm)
A/C is ON high blower speed
ECU will set the fan ON if the resistance of the sensor gets infinite resistance -open circuit-. Since it
has no reading, better have the engine cold than burning!!!
*FYI A/C compressor will not engage if coolant temperature is greater than 115°C, you can take this
as a sign that your engine is getting hot and something is wrong with the fan or thermostat, since it
usually lowers the temperature RIGHT away. Also, ECU will send the temperature light signal to dash if the
coolant temp reaches 118°C. Also, ECU will not engage the compressor if RPM>6000.

TOOLS: cheap 1K potentiometer, multimeter -better if it has thermocouple function, something to measure
temperature of thermostat housing if your multimeter has not thermocouple, cooler (for the beers)
- After my failed thermostat replacement I did the following:
1 - I had the fan verifyied before changing the thermostat, still I did it again, to check connect 12 V to
the fan terminals... should start right away.
2 - QUICK CHECK: see that both relays and ALL the wiring coming out from ECU is working... start the
engine... turn the A/C on on lowest speed, go to the engine bay and check for the fan to start (it should on
low speed), then go and put the blower to max, the ECU will send the HIGH speed fan signal (fan should
change to high speed, and you'll notice it). IF you don't have much time / curiosity, go to step 5.
Curious, time consuming check and beer time... detail double check
3 - Check the Engine Cooling wiring & relay from ECU to fan, easiest way with computer, I don't have it or m
entioned above, so nearest solution: remove A/C Relay (little one next to empty slot) and put a jumper from
the signal terminal (rose cable) of low speed fan relay to the high speed fan relay command terminal (orange
one), when A/C button is on (USE LOWEST BLOWER SPEED), it will emulate the signal that ECU would send if the
car gets too hot. If the fan starts. Remove the jumper and inset the relay in place.
4 - At this point only three posibilities left: 1.- Faulty wiring 2.- Faulty sensor 3.- Faulty ECU 4.-
Something clogged, I had replaced the sensor a few months ago that's why wiring was my first bet. Check
continuity on the two terminals of the sensor connector (cable) to the ECU, terminals 18 & 46 if ok, wiring
might not be the issue, but can still be a false. give it a jiggle to be certain.
5 - To test the ECU management (funny part), with engine NOT running, disconnect from the CTS and attach
the potentiometer to the cable to simulate the sensor, set it the highest resistance setting (1k), now,
start the engine (careful on the fan area, it will be start at sometime!!!), you can begin to reduce the
resistance of the pontentiometer gradually, you might see if the fan cuts in, also is worth to take a look
at the dash (or have a buddy with a beer looking at it) from time to time so you see if the fan cuts when
the needle is pointing the middle -as it usually does-. If this happens, and the value of the resistor is
around 170 ohm, ECU is doing it's job; if you keep on lowering the resistance -GRADUALLY- high speed signal
should be sent to the fan -around 140 ohm value-.Do not attempt to measure the resistance while the potentiometer is attached to the ECU, since the measuring will be incorrect, just put a mark on it when the fan starts and a second one when the high speed engages, then, remove it and measure the resistance at each of the marks!
-If anything of the above is O.K. and your hoses/radiator/pump are not clogged or damaged then, heaven may help you only...
-remember my simptoms were that the temp gage was indicating lower than it usually does I suspected the most about the wiring since the sensor was new, but wrong, the sensor was faulty... and trying to measure its resistance while installed is a complete crap work... but if you like to, you can try to measure it while the engine is hot enough (confirm the temperature in the thermostat housing). that should rule the sensor right away.
Cheers!