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RS blu

Fans do not turn off

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Hi, for a few days I have a problem with 1991 Esprit SE radiator fans,:( often the fans turn on about 80 ° c and they turn off when they want. Sometimes it works well, the fans turn on at 95 ° C and the coolant is at the right temperature when the fans turn off. If I turn the AC on, the fans work properly with AC cicle.
When the fans turn on at 80 ° C I have tried to remove the Rad Fan Control Relay' in the engine bay,but the fans are always on.
I also removed AC fuses and relays but the fans are always on.
Only if I release the Rad.Fan.Relay in the front luggage, then they turn off and the check engine turn on,obvious.
When the fans turn on ,also at 80°c,the check engine did not turn on,never.
Only once turned on the engine overheat warning,(coolant tell tale turn on,the coolant level was ok) but the temperature was not high, I turned off the engine and when I turned it on, the fans turned on at 80 ° C for the first time. The temperature gauge and its sender are correct.

 I have also tried replacing the various relays, but sometimes the fans work well and sometimes turn on 80 °c.

 Unfortunately my old computer with free scan does not work but I connected A and B in ALDL cable and I have no errors in ECM.:cry:

 

Do you think I should buy a new coolant temperature sensor switch (TCS)?

I tried to disconnect the wire from the TCS but the fans always run on.

 

I hope it is not the ECM, even because the check engine light never turned on.
Many thanks in advance, and sorry for my English, it's not easy for me.
Regards

Ciao
Roberto  from Italy

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Upgrade today to remove Google ads and support TLF.

Yes, I changed the relay. Sometimes the fans run well but often it turn on at about 80 ° C and turn off at about 75 °:(

 
 

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on other cars I have encountered similar issues.

removed and cleaned the end of the sensor, flushed and refilled the radiator and all was well.

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You do need to verify that your dash temperature sensor (at the thermostat) and your ECU coolant temp sensor (under the manifold) by looking at the ECU temperature using Freescan or Espritmon.

If they do not agree, then you may either have an air pocket, or one of the sensors is incorrect.

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Unfortunately I do not have a freescan anymore, but next week I will go to a friend who has the Tech1.:) I wanted to change the CTS by myself and try with a new one,but unfortunately it is in a bad position and I do not know how to remove it.:cry:

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I guys, unfortunately I think I have bad news.
I have not yet solved the problem fans, it only happens sometimes.
But unfortunately the car for two time turned off while I was driving.
After a few minutes it starts again and runs very well, the ceck engine never comes on and the petrol pump runs when I try to start the engine but it does not start or it turns on but when I press the accelerator it feels like it does not.
After a while it comes on and goes very well:cry:

I bought a new TCS, I have not yet mounted it, but when the fans turn on at less 80°c I disconnected the wires from the old TCS but the fans always rans, even if I connect the new TCS the fans turn the same.

I checked everything and found that the schematic of the manual is wrong, the rad. fan control relay in the engine bay is the second from the left, not the first.All the relays are OK, there's not  rust anywhere, and all the wires are perfect

In any case when the fans turn on at less than 80 ° C the current arrives at the radiator fans relay from the ECM, I connected a light bulb between 86 and 85.
I believe it is the ECM also because I had mounted a chip from puk, and the problem  occurs also with the original chip.Now I put the original chip back but when I connect the A and B poles of the ALDL cable, there are no errors but the fans turn on .I believe that the problem of engine shutdown is also due to problems in ECM.:(

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You could have a short in the wiring from the engine coolant sensor to the ECM. That would give a high reading, cause the fans to come and even cause shutting down and not restarting as the ECM tries to protect the engine from what it sees as overheating. You really need to get a reading of engine temperature via Freescan, Espritmon, T1 or such.

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I believe you could be right, but in this case it should turn on also the red engine coolant tell tale,the switch is the same.:(
I ran for a year with a chip from Puk, now I also tried to come back the ECU to original mencal. I would not have been the chip to create ECU problems.<_<
Do you think it's normal that when I connect A and B in the ALDL cable and turn the key to position 2 the fans turn on.There isn't any code error in ECU.
When i turn the key in position 2 the radiator fans turn on and the check engine flash 12 for three times .:cry:(only if I remove the wires from the TCS, then the error in ECU appears):(
 
Edited by RS blu

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Roberto, I missed this post and only found it after reading your recent post on Excelnet.

Yes, if you connect A & B to manually read the codes, the fans will come one, this is normal behavior, along with flashing code 12 to indicate there is communication. All described in the workshop manual, section EMH1.

You should get code 14 if the ECM recorded a high temperature reading, this is puzzling...

Filip

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Hi Pilip I am enclosing the images of the wiring diagram, one of the 1989-90MY with otter switch and one of 1993.5 USA MY which I believe is like my 1991MY.(I haven't got any otter swicth in my car)

I bought the car almost new from a friend many years ago, I exclude any kind of change on the relay position

I think the relays are reversed because when fans turn on  the current arrives from the ECM at the  second from the left and not on the first and if I remove the second relay the fans go off . I connected a light bulb between 86 and 85 in the relay support without the relay.( obviously in this case the fans turn off )

You're right, I've seen now that J3C5 is common for both TPS and CTS, so if it's not the ECU then it can be a TPS problem.

5abf8bd44e956_Immagine(7).thumb.jpg.78af9a6bb0a639623ed5af21ed580902.jpg

1993.5 without the otter switch

 

5abf8d6cce95e_Immagine(8).thumb.jpg.e39f7b86957bf6abdae78639fd050c71.jpg1989-90 with otter switch  

5abf8c63d259a_Immagine(9).thumb.jpg.5282bf005a6a04d4a94b9764a2187aad.jpg

Edited by RS blu

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Hi Roberto,

I have the same manual, for S4, Sport 300 and S4s. But mine does not include sheet 8b (not that I can find anyway). You are correct that your 91 SE is (should be) wired as per sheet 8, without the Otter switch. It must be a mistake in the manual, possibly someone forgot to delete the Otter switch from the drawing for the injection models.

I use a different manual for earlier cars, which is why I have different page numbers. The older diagrams are a bit harder to follow, but are actually identical. I have included the diagrams for both the carbed (with Otter) and injected.

As for the position of the relays, I agree it's annoying, but nothing to worry about, the mountings can easily be switched. If not by a previous owner (or mechanic), perhaps a harmless mistake in the factory.

Filip

1988 - 1992 Lotus Esprit Radiator fans.pdf

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many thanks Pilip, in fact there are some differences between my scheme and your one. <_<I think I will try to use yours.  I keep you updated.

ciao:)

Roberto

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unfortunately nothing:(
Today I changed the TCS, everything seemed to work fine, the fans started at 95, they turned off at 90 degrees. The car starts better in cold weather and the engine runs better at low revs. Unfortunately, after about 10km the fans turned on at 80 degrees and they are not turned off.:angry:
I'm embittered, next week I'm going to the Lotus dealer, but I do not have high hopes:(

Edited by RS blu

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Too bad Roberot...

I think your money would be better spent getting a PC for Freescan or Espritmon and log all parameters to check when it happens again. Chances are the dealer will have little experience with or patience for an 'old' Esprit...

Filip

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That’s not a good thing - and is a common sign the Ecu is bust.

you will need to check the wiring and relays first

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1 hour ago, Escape said:

Too bad Roberot...

I think your money would be better spent getting a PC for Freescan or Espritmon and log all parameters to check when it happens again. Chances are the dealer will have little experience with or patience for an 'old' Esprit...

Filip

Hi Pilip, fortunately he is an old Lotus mechanic who knows very well the Esprit, (he knows very well also the braking system Delco moraine):)Unfortunately he has many Esprit under repair now but at the end of the month he will have time for me.
Yes,I think I'll have to find a free scan. Too bad the car has always gone very well , I've had it for many years :angry:

39 minutes ago, Barrykearley said:

That’s not a good thing - and is a common sign the Ecu is bust.

you will need to check the wiring and relays first

I think so too, unfortunately, the lotus mechanic also told me that sometimes when the ECM breaks down it has similar symptoms.

I'll keep you updated, I've already checked all the relays and wires, however I'll try to check everything again

ciao Roberto

Edited by RS blu

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As the only other influence on the fans I can see is the A/C, could that perhaps be causing the issue?

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yes you're right, but I tried to disconnect the Air cod. relay and low pressure switch but the fans remain turn on:angry:

this weekend I will do other tests B-)

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hi guys, unfortunately I have not yet solved. The fans turn on at 80 degrees or less  and turn off when they want. I understood that the problem is between the ECM and the radiator fan control relay in the luggage compartment. When the fans turn on, only the radiator fans relay is switched on through the green purple wire that comes from the ECM.

I have changed the CTS but nothing has changed, sometimes only the fans turn on, sometimes the engine coolant tell tale warning light comes on too.The coolant level is ok and also the  the coolant temperature is right. I have also checked the ohms from the TCS and they are correct with the coolant temperature, the dashboard gauge is perfect,but the fans start at 780 ohms at 50 degrees, they should turn on at 95 degree around 200ohms.

When I turn  on the car from cold  the first few minutes the engine is correctly run at high revs, but when the engine goes to the idle the fans turn on and sometime also the coolant light turn on. Obviously the temperature is low, the engine runs only from a few minutes. I connected an old Tech1 but there are no errors in the ECM, I changed and exchanged all the relays, I tried to detach the trottle position sensor but nothing changed. I checked the wiring, they are like new.

I think it's the faulty ECM, but what can I do? I think the only thing I can do is send it to SJ , it's not very cheap but I think I have no choice. What do you think? If someone has some alternative please let me know ,thanks

Edited by RS blu

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