Been having issues with my fan not coming on for ages....really wanted to tackle it this Winter.
I have tried many things, but recently I read that I can force my cooling fan on by disconnecting the coolant temp sensor connector....a few questions I would like to ask for help with:

1. Do I need to reconnect the ECU? I had to disconnect to get access and it seem difficult to connect it and still have access to the sensor connector.

2. Does the car need to running or just have the ignition on? I tried with the ignition on and nothing happened. I don't want to start it as I have the airbox and filter off to access the connector. picture of the connector just to be sure I am in the right place.










3. if this does work, meaning the fan goes on when I pull the connector, what does that tell me? my fan works? will it help me diagnose why the fan is not coming on at the right temps (stage 1 or 2)? if so, how?

4. since everything is apart, should I just pull the sensor and test it w a volt meter and some hot/cold water?

5. if I pull it and test it, do I need to bleed the system? not that hard, but would guess I would not lose much fluid and it should self bleed.

thanks in advance...feeling a bit lost on this and don't want to assume something that ends up making my problem worse.

funniest part, even though the fans don't come on, the car runs a good operating temp, but I'd still like to get it fixed

 

Low speed fan comes on at 105c.

what temps are you seeing? Does it get up to 105c?

 

hi, thanks for the read and reply.

it runs at 188 - 192 most of the time...in normal driving situations it is a bit hard to get it over 215F.

I have driven hard and then let it idle in the driveway afterwards to see what happens....nothing!
the temp (scangaugeII in OBDII port) went to 214F (101C) and I was hoping I would hear the stage 1 fan come on...it did not.
I let it go to 223-225 and nothing happened (so stage 2 was not triggered either.

I'm going to recheck all fuses today.
thinking about pulling the cooling temp sensor to check that (not sure if the OBDII reading is from there...if so, it should be good).
Heat works so I do not think it is thermostat not opening.

another ideas?

I may just end up direct wiring the fan with a switch inside that I can turn on and off when I want to....thoughts...

Thanks again!

 

I've not had this issue yet on my mini...

however I have seen some reporting the engine cooling fan not working on YouTube. iirc there is a resistor on the fan assembly that goes out commonly.

one thing that crossed my mind was to get a used temp sensor from allmagautoparts.com and stick it in boiling water as a test.

I'd also test as much of the electrical as possible. see what kind of voltage you are getting at the plug. I can dig up a diagram if you don't have one

 

ssoliman,

thank you for the reply and ideas....I have the wiring diagrams, but am not great at reading them. I am working on that.
I just think I currently lack the knowledge of how it all works. I have some ideas, but can't seem to nail it down.

for example, I show a good coolant temp reading on my scan gauge 2...does that mean the coolant temp sensor is good as well? I would assume that, but don't know for sure (I have sent a question to SC2 to better understand where the unit gets its readings).

I think the fact that the heat works indicates that the thermostat is good.

I have check all fuses and tested all relays.

I also am unsure if 12 volts would run to the fan at all times or just when it is triggered by the ECU when it is seeing the indicated "turn it on" temps.

the only thing I know is that if I put 12v to the fan (it is brand new, so the resistor is good) it works. I am at a point that I may just direct wire the cooling fan and turn it on when I see the temp get high on the SC2 with a switch in the car...even that will take some work on my end, but I am confident I can figure that out.

ugg...I love this car, but there are a few things that drive me a but nuts!

 

I'd strongly recommend fixing what's broken rather than hack into the wiring.
So we know the sensor and fan are good. Are you sure you checked the "correct" fuses and relays? The ones in the box under the hood, not the ones in the footwell.
Try removing the fan relays and measuring for 12V at all the input terminals (4 total). Try shorting the terminals to push 12V to the fan and see if the fan comes on. With the engine hot enough to trigger the fan, see if the coil output terminal for the stage one relay is getting pulled to ground (this is how the DME triggers the relay).
If everything checks then it points to a bad relay; try switching the first stage fan relay with the AC relay to see if the relay is faulty.

 

mrbean,
I agree...I'll keep poking around to find the issue and get it fixed. the direct wire would be last last resort.

so, yes, I checked / bench tested the fuses and relays under the hood...I also switched the relays...but now that I think of it, I don't think I let the engine get hot enough after the relay switch to have the fan come on...ill have to try that.

the rest of your post is a bit greek to me...i'm just not great or confident with the wiring / electrical systems. I have a buddy that is though and will share with him to see if I cn get him over to check it with me...

I appreciate the info and suggestions!

 

I hear you, Sir. I don't know as much about the functions of the cooling fan either. I could know more for sure.

I like mrbean's suggestion. Basically jump the 12v and bypass the relay at the fuse box. One wire connecting what would be connected if the relay was know to work.

Also had another thought. When the ac is on the fan should come on (to cool the condenser / compressor), then go off, then come on...and continue doing that. Is it?