'07 C6 Vert stick shift
71k Miles
Driven in a 105F enviroment

I had an overheating issue prior to this. Here's a reference to that

https://www.corvetteforum.com/forums...erheating.html

The fan is direct-wired as of now to avoid overheating. Any potential problems for running a cooling fan direct? I need to get it fixed asap because its my DD car. I have schedueld an appointment with the chevy dealership this coming Saturday but before I head out over there I need to know if the problem is fixable without having the need to spend all that extra $$.

Now what could be a possible culprit? The fan is good since its running direct for last two days. So now its either the wiring, ECM or the PWM( Siemens fan controller). There's no connectors in the fan wiring (except for the PWM fan controller connector) but just a couple of joints probably from the previous owner who might have ended up with a molten connector and decided to get rid of the connector and simply electric tape the joint.

When I pulled out the fan assembly earlier this week while replacing the water pump and the tstat, I tested the fan controller (Pulse Width Module [PWM]) by connecting it direct with a power source (car battery) the fan turns when the negative wire was being touched and removed then touched again and removed (mimicking the square signal system that the ECM sends under normal conditions to dictate the fan duty cycle). This could mean that the PWM is good

So is the ECM going bad or is it the bad wiring full of joints and electric tape thats causing the fan not to run.

Another problem is the temp gauge fluctuations while driving, it drops down to a point where it says coolant temp low (130F) stays that way for a while then immediately shows a reading of 200F-200F (the normal temp). And if this wasn't enough there are two more messages that keep popping up but weren't there prior to this fan/ overheating issue. those two messages are "Check oil level", "Oil temp low". I did an oil change today and still its the same. Does this all indicate one thing? A bad ECM??. I highly appreciate any feedback. I'm sure its going to help me plus a lot of us who have ran into a similar situation or might encounter one.

Post#13 of this thread has some good info as well
https://www.corvetteforum.com/forums...oling-fan.html

 

If the 130 then 200 temps - showed up after you did water pump I would check to see if you filled the system with coolant and do no have an air pocket. If it was happening before maybe get a new sensor.

 

Avoid dealer. Zero reason to pay a dealer for something like this. They will do you hard with no lube.

If you can't deal with it yourself, then find a good local LS shop.

ECM is probably not the issue. Have you confirmed no head gasket issue? Confirmed it wasn't just overfilled and is no long an issue. You are not even clear what the problem is. If the fan is operating, then the fan/pwm/ecu is not an issue.

 

Make absolutely sure you got it full of coolant.

I'm not sure yet because I haven't done the coolant on the C6 yet, but on most other Chevy small blocks I've worked on, pulling the coolant temperature sensor when filling the cooling system is a good "bleed" point to let the air out as it fills.

Also, boiling coolant and loss of coolant are often the symptoms of a bad/weak pressure cap. The cap is inexpensive enough, just toss a new one on the thing. I rarely advocate "throwing parts at it," but that's one part I just toss. I also consider that a maintenance item, and routinely replace the pressure cap every 2 to 3 years.

 

Fan is running because its hot wired. I removed the PWM connector and direct-wired the fan. If I connect the PWM connector, the fan never turns even with the A/c on. The car isn't overheating now anymore because the fan is running at full speed at all times. I'm afraid running the fan direct at full might burn the fan motor thats the reason I need to get the fan working normally.

 

I replaced the reservoir cap 2 days earlier along with a new water pump and a tstat. I'm pretty much sure its a faulty sensor but I'll try bleeding the coolant once more just in case before replacing the sensor.

 

The fluctuation was there prior to the coolant change so I'm quite confident its the coolant temp sensor but I'll try re bleeding because anyhow I need to refill it with Dexcool, I'm currently running on distilled water

 

So the search is further narrowed down. PWM module (Fan controller), ECM etc all good.

First) Its the Cooling fan motor that is drawing high amperage. So if the 60A (#25) cooling fan fuse isn't direct it wont run. A 100A fuse does work but the electrician said its the fan motor that's drawing high amps. So even the 100A fuse won't be helpful in the long run as the motor will gradually draw more & more amps and suggested the best fix is to replace the fan motor.

Secondly) the coolant temp sensor needs to be replaced the gauge is fine but the senor is faulty and keeps fluctuating.

The rest all is good. The wire for the oil sensor was disconnected and that's fixed.

Now the OEM fan is just way too expensive. Is there a way around. A friend of mine suggested I try tossing in a Mustang fan. Any suggestions?

 

Used fan should be super cheap

 

The best price I see on a GM (or AC Delco "Original Equipment") Radiator fan assembly is about $245 at RockAuto. That's $257.79 less a $12.89 discount. That's about $100 less than any online source for the GM Part #, and better than Amazon by $30 or more, even with shipping. To get the extra 5% discount at Rock Auto, put 6869560248874231 in the "How Did You Hear About Us" box at the bottom of your shopping cart page. That discount code works on everything at RockAuto.com, not just your fan, and it's valid through the end of October, I think.

Oh, the part number for the fan assembly you're looking for is AC-Delco 1580657 or GM 15819952.

There are "after market" alternatives, but my experience with after market electric fan assemblies is that they all underperform. So called "High Performance" radiator/cooling fans tend to be the worst of the bunch.

If budget is an issue, I'd take a used, genuine GM fan over the aftermarket (new) alternatives. Hit http://www.car-part.com/... for a list of potential used parts sources. That site is a database that aggregates information from thousands of used parts sources (yards and dismantlers) all over the USA (maybe the world). Most yards don't keep their inventory on that site very current, so the parts shown are often gone (from the stock # or specific donor information on the site), but usually within a few phone calls, you'll find someone who actually has the part you need.