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AU I temperature sensors 

 

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 Post subject: AU I temperature sensors
Posted: Wed Dec 30, 2009 10:41 pm 
Tyre Shredder
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hi folks, was wondering if anyone knew the resistances of the coolant and air temp sensors with temp?? or just the part numbers??

if anyone knows the biasing resistor values inside the EEC-V too that would be swell.

i measured the sensor resistances (with the ECU connected tho) then the voltage:
Code:
sensor         resistance       voltage         temp     
coolant        7.81kohm         1.861           50
air            790ohm           2.985           24


i worked out the current then the voltage drop across the unknown resistor lalala (and double checked with the potential divider rule) to give

Code:
ECU:
coolant biasing resistor:         42.550Kohm       
air biasing resistor:             876ohm     


is there any chance anyone could confirm these numbers (its possible the resitance values may be different since i didn't disconnect the ECU to measure them)

 

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 Post subject: Re: AU I temperature sensors
Posted: Thu Dec 31, 2009 3:35 pm 
Tyre Shredder
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Hi folks

This is what i managed to come up with, not as accurate as i'd like but should be suitable for an aftermarket computer, i used the voltages specified in the technical documents section on the EEC-V (although that was for an EF, http://www.fordmods.com/documents.php?d=42). From my own measurements i determined that the internal biasing resistors in the ECU must be 43K +/-10% for coolant and 2.4K +/-10% for the air temp, thus:
Code:
air temp -bias 2446 ohm
0C     3.9V     1146ohm
20C    3.1V     831ohm
40C    2.2V     537ohm


Code:
coolant temp -bias 43503 ohm
20C    3.1V     14776ohm
20C    2.2V     9545ohm
40C    0.5V     1855ohm

 

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PH 4480 racing extractors
lukey 2.5" sports exhaust
Chopper 19"x245 mags
pioneer deck, 6"x1.5" Splits (F) and 6" 3-way speakers (R)
Precision response 4x 100w amp and 1000w mono 10" sub
Got so much more to go!
tint, breaks and spoiler next!

Last edited by bradders on Thu Dec 31, 2009 4:23 pm, edited 1 time in total.

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 Post subject: Re: AU I temperature sensors
Posted: Thu Dec 31, 2009 4:22 pm 
Tyre Shredder
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it appears that no one seems particularily interested. but i've just noticed that the ECU switches its biasing resistor once the coolant temperature starts to get hot ~80C.

 

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lukey 2.5" sports exhaust
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pioneer deck, 6"x1.5" Splits (F) and 6" 3-way speakers (R)
Precision response 4x 100w amp and 1000w mono 10" sub
Got so much more to go!
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 Post subject: Re: AU I temperature sensors
Posted: Thu Dec 31, 2009 4:36 pm 
Getting Side Ways
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10C--58.75kohms
20C--37.30kohms
30C--24.27kohms
40C--16.15kohms
60C--7.60kohms
80C--3.84kohms
100C--2.07kohms


Ign on coolant temp sensor
engine at 20C---3.1V
engine at 40C--2.2V
engine at 100C--0.5V


Ign on intake air temp sensor
engine at 0C--3.9V
engine at 20C--3.1V
engine running air temp at 40C--2.2V

 

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 Post subject: Re: AU I temperature sensors
Posted: Thu Jan 07, 2010 8:51 pm 
Tyre Shredder
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Cool thats really handy! thanks for that! how'd you get all that info, did you work it out empirically or did you have a handbook?

The voltages are handy. However, i noticed that the voltage jumped to like 4.5 once the engine started to get hot like ~80-90C. I had assumed that the EEC-V had switched biasing resistor to match the lower resistance range at the hotter temperatures to allow for higher resolution (due to the logarithmic nature of the NTC thermistor) but it would make sense that if there was an open circuit the signal would match the reference voltage source in the ECU, i had assumed it would have been 12V, but since most microcontrollers are 5V perhaps the reading of 4.5V does indicate an open connection to the sensor for some reason.

 

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PH 4480 racing extractors
lukey 2.5" sports exhaust
Chopper 19"x245 mags
pioneer deck, 6"x1.5" Splits (F) and 6" 3-way speakers (R)
Precision response 4x 100w amp and 1000w mono 10" sub
Got so much more to go!
tint, breaks and spoiler next!

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 Post subject: Re: AU I temperature sensors
Posted: Thu Jan 07, 2010 9:15 pm 
Getting Side Ways
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Temp sensor, Tridon part No TCS134

However the air sensor is combined with the MAP sensor (T-MAP)

 

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