Coolent Sensor Problem

[ausbundyjr]

Hey guys, I thought i would investigate why my thermo fan never turns on. Made up an ALDL cable, used WinALDL to have a squiz a the sensor data and found something interesting...

When cold, then Coolent Temp. started at 77.1C, and went DOWN linearly as the engine warmed up, by the time its hot (and i get to work) the temp data says 27 C.

Threw in a new sensor today, and still same issue, numbers go down as engine heats up.

Has anyone seen this before or know what else i can look for?

Gotten me quite confused.

(btw, no error codes, cooling system flushed and cleaned, new thermo, VN V6 S1 Man.)

Cheers guys, hope we work something out.

ps and i have all the tools i may need to test anything, so dont hold back on possible ideas

[delcowizzid]

fit a 2nd hand $20 ecu or borrow a mates ecu

[ausbundyjr]

yeh might have to find another ecu to check with, but strange that the numbers change inversly...

see what i can find locally

cheers

[delcowizzid]

the coolant circuit in the ecu is a known bad part quite often does weird stuff

[ausbundyjr]

oh i see, you wouldnt happen to know exaclty what goes bad in them would you? i can fix some circuitry at work, but id probably be better off just gettin another ecu from a wreckers wouldnt i? (save time)

cheers

[delcowizzid]

its a resistor for the coolant sensor circuit normally but sometimes its the tracks of the ecu itself the later vr ecu's had way better track material open a vn on the tracks are all bubbly open a vr ecu and its nice and smooth

[ausbundyjr]

alrighty thanks mate, i shall have a look in it tomorrow at work and see if we can find anything.

thanks for ur help

cheers