2004 Crossfire Convertible.

Hi guys,

Recently replaced water pump and new antifreeze - all went well apart from damaging the connector on the coolant temperature sensor. Upon driving the car the fan came on straight away from cold and remained on, the dashboard temp. gauge would not move from zero once the engine got warm, and the engine management light was showing on the dash. The pump was replaced with the fan in situ and I'm sure I didn't damage or disturb this.

I've replaced the coolant temp. sensor, and now the dashboard temperature gauge works fine, but the fan is still coming on from cold (you can hear it inside the car) and remains on, and the engine management light is still on.

I've had no problems with the fan or the dashboard light until replacing the water pump - the only thing I noticed about a week prior to changing the pump was that the aircon didn't seem to be cold. I'd presumed it needed a re-charge and was intending to do this at a later date as it's only used for about 2 weeks a year in the UK. Not sure that this would be linked to the fan/light problem.

I thought there could be something wrong with the cooling fan module, however it would be a bit coincidental for this to fail during the time the vehicle was stationary during the water pump replacement.

Any ideas/help would be greatly appreciated.

 

You don't by chance have the A/C button pressed, do you ? ( That will make the fan run )
Short of that, about all I could advise is download the service manual from the below link and refer to "cooling" - "radiator fan always on"

 

Hi,

Thanks for your reply and the download link. I've checked that the A/C switch is off, so it looks like I can rule that out, also the engine management light remains on. I'll check the fan/powertrain module connections just in case there's a bad one or any have become disturbed during the water pump replacement.

I've a feeling this is going to one of those head-scratchers. Just hoping that I won't have to take it to a garage to have the engine management code diagnosed, as I've read of a few bad experiences owners have had regarding the cooling system (misdiagnosed FCM/PCM faults and unnecessary replacement parts fitted).

 

Solved

Just a quick update on this problem.

Disconnected the positive battery lead this morning and left off for a couple of hours whilst I did some other stuff. Put the lead back on and now the engine management light has disappeared and the fan is operating as normal. The system must have needed to reset itself I guess.

Only small issue now of getting the circlip back into place to hold the replacement temperature sensor firmly. It's a bit of a squeeze in there - seems to be a job for small fingers (or a micro surgeon).

Nevertheless, I'm very happy. First time I've ever done a water pump - job completed for less than £50

 

That's great !!!
You did mention that you did the job with the fan assembly in place, 5 minutes to remove and re-install the fan would have saved you much more time, aggravation and skin on your hands.
Sorry I overlooked the system reset, usually the first thing recommended.

 

I agree. I was a bit reluctant to remove the fan as I'm such a novice at vehicle repairs and wanted to take off as little as possible, but yep, I'd certainly do so in future as it is so easy to remove.

Must say a big thanks to everyone who has posted pics and information on the forum regarding water pump diagnosis and replacement procedure. I know it's probably only a small job to many, but it gave me the confidence to attempt it, and it feels great to have completed it successfully (whilst saving a fair bit of money at the same time).

Cheers.

 

Sounds like the PTCM or the FCM got caught in a weird "state of mind". I'm wondering why, but who knows - anything with a microprocessor can 'get into a bad loop'.

This is how the fan works:

The PTCM sends very short pulses to the FCM periodically. The FCM responds with pulses - so long as both modules see the pulses from the other, all is well. If the PTCM wants the fan to run, it makes it's pulses longer, but the FCM responds just the same, - with a pulse in reply to each one sent to it by the PTCM.

Now, let's say the wire between the modules goes open, is cut, or what ever. The FCM won't see the pulses and will 'know' that it has no instructions on how fast to run. So, it goes into EMERGENCY MODE. It runs the fan at full speed at all times to protect the engine. At the same time, the PTCM won't see pulses from the FCM, so it lights the little radiator light, indicating that it senses a failure with the cooling system (the failure is that it can't communicate with the FCM).

If your CHECK ENGINE light came on and NOT the Radiator light, that would be an indication that the PTCM was off in looney-land, not sending pulses to the FCM and (probably) not doing other stuff as well. Yes, you did reset it, kinda like rebooting your PC.

 

Good job on figuring it out

The damaged temp. sensor wasn't able send the engine temp to the ecu... the ecu (not knowing the engine temp) activated the electric cooling fan to "save" the engine from over heating. The ecu had to be reset/code cleared for it to function properly again... Basically what others have said.

 

If you don't mind me asking, can you tell me how you removed the temperature sensor mine seems to not want to come out

 

He wo'nt mind you asking, cause he will never know you did - click on his username, then click on "View Public Profile" and look.............he hasn't been on here since December 2014. Not sure who else can help.