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I have a 07 Z06 that is track focused. I removed the AC system and now the radiator fan seems to stay on. I suspect due to missing AC system, but not certain of that. Will the fan turn off once the car is moving? I'm concerned about over speeding an energized motor when the car is on the track.
Did you remove the HVAC controller as well? Were you using the A/C the last time you drove the car before removing it? The HVAC controller sends a class 2 serial data signal to the BCM when the A/C is on. If you removed the HVAC controller perhaps hook it up briefly and hit the A/C off button. Wait a brief time then unhook it.
Did you remove the HVAC controller as well? Were you using the A/C the last time you drove the car before removing it? The HVAC controller sends a class 2 serial data signal to the BCM when the A/C is on. If you removed the HVAC controller perhaps hook it up briefly and hit the A/C off button. Wait a brief time then unhook it.
The HVAC controller is not removed and is off. Thanks for the tip.
Present state:
- ECM/BCM reading 100 psi via resistor arrangement on pressure sensor plug.
- Fans tuned out in that pressure range. 600 - 825 kpa = 0%
- ECT well below fan threshold (cold).
- ECM/BCM commanding fan on at 9.8% constantly,
- Fan 1 is commanded "on".
I'm at a loss, so I scheduled an appt with a nearby Chevy service dept that is friendly to modified cars. The intent is for their scanning equipment to identify the source of the fan running.
Usually 10% is the minimum speed of the fan with 90% being full speed. Is it spinning slowly?
Your 100psi reading at the pressure sensor is well below the 160psi setting for the fan to start running.
Engine coolant temp of 204 degrees starts the fan at 10%.
Engine oil temp of 302 degrees commands the fan on at full speed.
Transmission oil temp of 270 degrees commands the fan on at full speed.
Has anybody modified the fan tables in the past?
The fan is running slowly. As for tables, they matched OEM until I modified the Desired % vs. AC pressure table just to ensure that wasn't causing the problem. I've been through the tune with HP Tuners and don't see what's causing the problem. I even tried disabling AC via TPS & RPM settings. Oil and Trans are ambient temp when the car starts. The behavior starts as soon as the engine starts with everything completely cold.
I was informed by a company that builds c6 based race cars that no tune modification should be necessary. Just unplug everything relevant. As-is, the AC pressure sensor and compressor are unplugged. I'm starting to wonder if this isn't caused by the AC removal. I did a lot of work to the car over the winter. Front/rear cradle both out for clutch replacement and some other work. Maybe something else got missed or broken?
Sounds like it could be the fan control module if you inspected/cleaned all the ground connections at the module and ECM.
Most people don't know this.......Ford also used these same modules in the Ford Fusion. I'll update this thread shortly with the actual part number and year to look for in the wrecking yards. Always a good idea to have a spare one for trouble shooting.
Thank you! I really appreciate it. I haven't bought a FSM yet. I really should. I've been signing up for the 3 day subscription on the ACDelco TDS site when I really need it. That table leads back to the ECM... so perhaps something in the tune.
HP Tuners scanner has Fan1,2,3 channels that indicates the state the ECM wants the fan in (I think). Fan 1 = on, Fan 2 & 3 = off are always shown. That indicates the ECM/BCM actually want the fan on. The spinning isn't a result of stray current or some misbehaving module.
I appreciate the compliment, however it seems I'm squarely in the "knows enough to be dangerous" category still!
I would recommend replacing this module first. If it turns out this wasn't the problem you'll at least have a spare for the future. I'm sure you could find one at the wrecking yards for $40 or so. Much cheaper than the Corvette version.
A spare E38 ECM from E Bay loaded with the stock vin tune can be had for about $149. I can give a recommended buyer I have dealt with in the past if you need one.
Both of these options would be cheaper than taking it to the dealer.
I even have a current 5% off code from Rock Auto if you purchase from them.
If you have your own J2534 tool than I can give you the part number for the correct used 2007 Z06 E38 ECM to buy at the wrecking yard. They are probably about $50 used. They were used in many other GM models.
If the dealer replaces both of these items the bill will be more like $750. Most likely they will not be in stock either...lol
Thanks again. That's some very useful information. As for the dealer, the ONLY thing they are doing is scanning/diag work. HP Tuners scanner doesn't provide data from all the computers, so I just want them to use their diag tools on it. They aren't doing anything else. Depending on what they, or me, find.. I may take your advice.
All 06 and 07 C6 Corvettes use the E38 ECM #12597121. The first picture shows my pen pointing to this service number. This is the back of the ECM. Second picture shows the front side. These ECMs were used extensively in 06 and 07 GM vehicles. They are easy to find at a wrecking yard. Expect to pay about $50 or so.
The only problem is they are currently loaded with the software from the original vehicle. Once you purchase one ....you'll have to somehow find someone to upload the C6 Corvette software to it. They will use your VIN number to upload the correct software. GM charges about $45 for access to this software then who ever does it for you will also charge their own fee. You can find people that offer this service locally on Facebook market place. If you have your own J2534 tool you can do it yourself.
You can see in the second picture I pulled this one from a 2007 Chevrolet Equinox.
You can also buy these ECMs on E Bay for about $149 pre programmed to your vin.
The AC removal did not cause my fan to run. My tune had non zero values for the lowest temperature value in the 18030 (Fan Desired Fan % by ECT) . The lowest temperature's desired fan % is applied to ALL ECT values up to and including itself. e.g. 192.2 F = 50%. Fan runs at 50% until the coolant gets above 192.2 F, then the next cells value is applied. The fix was setting the table back to OEM, which has a 0% for 192.2 F & 195.8 F which are the first 2 cells in the table (L -> R).
Once the 18030 table was corrected, I could not get the fan to run from anything related to AC. No tuning or modification should be necessary to prevent the radiator fan from running contiguously when the AC system is removed.
Track build radiator fan
