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Discussion Starter · #1 ·
Hi all!
I'm currently working on my 2004 135. Previous owners have done a number on the loom specifically around the dash to install various bits. So much so that it was basically a fire hazard and fault finding was near impossible.
So...
I have bought a loom from mgfandtfbitz and I'm pretty happy with it. Only some minor blemishes easily tidied.
I have spent a few days stripping down the old and installing the replacement.
*minor difference I found was the replacement did NOT have wiring for the exhaust volume sensor. Not fussed it's disconnected anyways.

Since install the car runs drives and works, except:
Engine bay fan runs constantly rather than when gets hot. I obviously don't want to deal with a burnt out fan or any other problems so looking to correct it.
First check was at the bay sensor which the new loom has the wires/plug for but I see that the replacement loom has a black wire and a black/green wire. First sign of alarm as they are different to the original. I've since been through a lot of testing/comparison to the original and I'm drawing blanks.
I've replaced the sensor. (Incidentally, just thought are there variations on these? That said they should still work in cool startups)

-Closing the loop bridging sensor doesnt turn off fan.
-Sensor checked for ohmage and looks to be good (old sensor and new)
-black lead solid earth to chassis
-green/black lead reads about 10.5v with battery on, solid connection to ecu.
-ECU worked fine when originally disconnected. (This is a KMAPS modded which again, worked fine days before)
-only difference in loom is it's missing the evc valve connection which isn't part of the situation.
-all bonnet and cabin fuses and relays good.

Anything I've missed? Will all sensors wires still be in the same ports on ecu? Anything else that will trigger the fan? (I've not touched the engine loom but that may be next on the list.

Help! Please!
 

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Slightly confused as an 04 car shouldn’t have an engine by sensor as the ECU uses other sensors to work out if the fan needs to come on. It would also be unlikely to have a exhaust valve.
 

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Discussion Starter · #3 ·
Was just reading another recent thread about coolant sensor on engine. MEK000030. Will be my next check tmrw.

Maybe this is the issue that all isn't as it seems.
I assure you the engine air temp sensor was there before and unplugging fired up the bay fan. Also the exhaust valve system is there, plugged closed and now unpowered. (Leading me to believe the kmaps was working correctly without physical mods)
I've studied the removed loom and theres no special wiring that I can see.
 

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Very interesting for me as you mention a Kmaps remap.

I bought a KMaps remapped ECU last June and fitted it to my TF, the performance was there for sure but similar to you the fan in the TF constantly on. I I returned the ECU put my original ECU back in the car and the fan stopped.

I then purchased a SAWS remap and fitted that and all has been good since, improved response and performance and no fan constantly on.

I had a constant fan on in issue in my F a few years ago and as Chris alludes to it was the failure of the engine bay sensor up near the expansion tank.
 

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Discussion Starter · #5 ·
Interesting. Then sensors aside I'm wondering if something has been modded somewhere. Just dont see why it originally it worked as it should. I'll check back around the wiring, fuse box and relays.
I'll open up the bay and look at the coolant sensor with the multimeter.
 

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Interesting. Then sensors aside I'm wondering if something has been modded somewhere. Just dont see why it originally it worked as it should. I'll check back around the wiring, fuse box and relays.
I'll open up the bay and look at the coolant sensor with the multimeter.
Given what I experienced I would start with removing the Kmap ECU and trying a standard one in there..........I wager that is the issue.
 

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I also had my ECU remaped by Kmaps and had constantly running fan when warm, switch to standard ECU and problem gone, also OK when running SAWS map. There was a checksum error with Kmaps ECU when OBD2 codes read.
 

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I also had my ECU remaped by Kmaps and had constantly running fan when warm, switch to standard ECU and problem gone, also OK when running SAWS map. There was a checksum error with Kmaps ECU when OBD2 codes read.
Good to have confirmation it was not just my car with the KMaps issues. Impressed with the SAWS remap brings the car alive and far more responsive.
 
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