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Discussion Starter · #1 ·
Hi I've been doing up my convertible after an year off the road.. and I blew a large hole in the radiator so had to get a nice new shiny one !! After putting it in I realised the engine was running very hot and the fan wasnt switching on.. So I checked the relay and it was fine, shorted between the 30 and 87 terminals and the fan came on, anyone have any help in where else I should check ? Would the thermostat not working cause the fan not to come on.. ?
 

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Hi I've been doing up my convertible after an year off the road.. and I blew a large hole in the radiator so had to get a nice new shiny one !! After putting it in I realised the engine was running very hot and the fan wasnt switching on.. So I checked the relay and it was fine, shorted between the 30 and 87 terminals and the fan came on, anyone have any help in where else I should check ? Would the thermostat not working cause the fan not to come on.. ?
Not sure on the NA cars, but the T5 turbo cars use two engine temp sensors, one for the fan, the other for the gauge/ECU.

So, I'd start there and look at the engine temp sensor(s)
 

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Hi I've been doing up my convertible after an year off the road.. and I blew a large hole in the radiator so had to get a nice new shiny one !! After putting it in I realised the engine was running very hot and the fan wasnt switching on.. So I checked the relay and it was fine, shorted between the 30 and 87 terminals and the fan came on, anyone have any help in where else I should check ? Would the thermostat not working cause the fan not to come on.. ?
With your Haynes open to p 12-16, I'd continue with the trouble-shooting..
Not that your t-stat is good, but, it has no control over the fan.
 

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Yeah, again the T5.5 turbo cars (but possibly true for motronic V6's as well), the ECU has a coolant temperature sensor, but there's a second one on the back of the engine block that feeds the ICE (integrated central electronics). This sensor feeds ICE which in turn outputs to the engine temp gauge in the dashboard instrument cluster and also controls the low- and high-speed fan relays. I assume these design is common to all NG900s...
 

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Discussion Starter · #6 ·
Yeah, again the T5.5 turbo cars (but possibly true for motronic V6's as well), the ECU has a coolant temperature sensor, but there's a second one on the back of the engine block that feeds the ICE (integrated central electronics). This sensor feeds ICE which in turn outputs to the engine temp gauge in the dashboard instrument cluster and also controls the low- and high-speed fan relays. I assume these design is common to all NG900s...
that is very helpful thanks, the temperature gauge on the dashboard is going up and down but the temperature could be wrong... the sensor on the engine block is in need of checking 1st I think.
 

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So, I don't have WIS or my Hayes manually in front of me, but google found a thread in which someone states at 20C/68F, this sensor should show 2400 ohms resistance.
 

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Discussion Starter · #8 ·
So, I don't have WIS or my Hayes manually in front of me, but google found a thread in which someone states at 20C/68F, this sensor should show 2400 ohms resistance.
Thanks again, I've just had a quick look at Haynes manual and is saying the same. How would I determine the temperature of the coolant though :roll: !!
 

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Discussion Starter · #10 ·
will do that, I'll get a reading at normal temp then get it to running temp and see if resistance has risen.. have just found a replacement on amazon for £9 which is about $15.
 

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Discussion Starter · #11 ·
Just finished getting it working, the sensor needed replacing !! No resistance reading on it.. The temperature sensor is sealed with cable attached and gives the reading for the gauge on the dashboard and the wiring to the ECU, there are 2 different sensors with different threads for the 900, if you need to replace one make sure you get the right one. Thanks again for the help. On to the next problem now...
 
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