Ok, I've searched and read a bunch of threads, but still haven't found the info I'm looking for...

Car is an '05 w/ 60k miles. A few weeks ago, the fan stopped working, and I was able to get the car home w/o overheating. Bought the car used last year, and as far as I know it's never been tuned (stock except for a cat back).

1. The infamous 'melting connector' is fine.

2. Fan runs when given 12V directly.

3. Power to fan control module is good/ fuse is good.

So, I ordered a new fan control module and installed, fan still won't turn on. I've run it up to 240*, w/ AC on, and fan never turned on.

So...

Is there a way to check the control wire into the fan control module to see if the ECU is commanding the fan on without a scan tool?

At this point I'm assuming the ECU is not commanding the fan on, but anyone have any other ideas?

I was actually hoping this was going to be the last repair I had to do on this car, as I was planning to trade it in tomorrow. I really don't want to have to sink even more money in it.

Edit: Also, is there a way to 'spoof' the command input to the controller to get the fan running?

 

both fans not coming on or just one?

did you really look at the connector.... unplug it etc or does it just "look" OK

 

Both fans? As far as I know, there's only one, but no fan is coming on.

Connector unplugged and checked. It's fine.

 

HPtuners can force the fans on. Get someone to try that. That being said, I bet it isn't that. I would cut the connector off and by pass it.

 

A continuity check that bypasses the connector plug will confirm if it's making good connections or not. Just check each wire individually and use a jumper on the one that doesn't work. Been there, done that. Pretty simple to check and fix.

 

You guys are talking about bypassing the three wire connector on top, before the fan control module, right?

 

The C6 only has one fan from the factory.

 

yeah, that's what I get for dealing my C5 much more than my C6Z06

 

Yep! That's the one. Even though it may look good, the internal wire may be broken, so do the check like I mentioned and if you find a bad one, simply use a jumper to bypass the connector. Every heart surgeon knows how to do it.

 

Working correctly, the fan will be commanded on as soon as the A/C is turned on..no need to wait for the radiator to heat up to test the fan etc.

 

Fan did not turn on with A/C. I switched the A/C on/off several times attempting to get it to do so. I saw in one post that the A/C has to reach a "certain pressure" to command fan on. Another said the engine had to be "up to temp" with the A/C on. Not sure if either is correct...

Anyone know at what temp the fan should be turning on?

 

I just went out and started mine and turned on the A/C. Engine cold and fan blowing cold air inside, the fan did not come on, so it must be that the engine is up to temp to get the fan to be commanded on. There are people on here who know exactly what parameters turn the fan on...I am not one of them, unfortunately. Sorry I couldn't be more help...

 

I got a hold of a friend who was able to borrow a scan tool from work and had him bring it over tonight. While I was waiting, I did some more continuity checking. The upper connector (the 3 wire connector that usually melts) was pristine, but I determined there was some wiggle in the ground connector on the male side, so I cut them off and hard wired the harnesses together, just to be on the safe side.

While doing that, I found the problem: the ECU signal wire was broken about 6" from the connector, up inside the rubber shroud, between the connector and fan control module. There wasn't a mark on the shroud, but the wire looked like it had been cut most of the way through with a side cutter, and finally pulled apart. Wonder if some UAW toad was pissed off that day...?

Anyway, got it all spliced back together before my friend showed up with the scan tool. Turns out the fan control module was fine, so I've got a brand new one to sell now. We let the car warm up, and played with some stuff on the scan tool and hopefully this info will help someone else:

The engine has to be up to temp (~150+), and the A/C has to achieve some pressure before the fan will command on, so you can't just start it, turn the A/C on and expect the fan to come on. It will start very low, and come up to 10-15% by ~180*, so you'll have to feel for air moving, as it's pretty quiet.

With the A/C off, the fan turned on at 198*, and did the same as above, coming up slow. We didn't run it much higher than 210*, and at that point it was running ~20%.

Thanks for the ideas, and hopefully someone will get some use out of this in the future. As for me, this is the last straw with this car. I've never had a car have as many problems as I have with this 'Vette. Mechanical breakdowns, electrical gremlins, overpriced cheap *** crap parts, and downright shi**y engineering. It's a shame, 'cause it's everything I want in a car, but I'm tired of fixing it. Hopefully by the weekend it will have been traded on something dependable.

 

Glad you found the problem and fixed it. Looks like HOXXOH got it right! Good info for all of us on the fan...I was always under the impression that the A/C just automatically made the fan come on...good to have the correct info. Sorry the car has had so many problems.