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Question: Cooling fan sensor

Mike74

Member
Joined
Nov 6, 2013
Messages
6
Location
California
Corvette
1994 FIRE RED
I have a 94 corvette LT1 base model and I'm trying to install a cooloing fan kit that will turn on the cooling fan at 200 degrees. According to the instruction the cooling fan sensor is located on the driver side cylinder head between 1 & 3 spark plug on this particular year but I dont see any sensor on the driver side. There is a sensor (single wire) on the right side between 6 & 8 plug but according to alldata that sensor is for the temp. guage. Does anyone knows where exactly the cooling fan sensor for this year? Tnx.
 
Moving from the Site Help and Feedback forum, to the C4 Tech forum.....
 
Sensor

The kit comes with a new sensor and harness. By unplugging the old fan sensor harness and connect the new harness on the new sensor and tap on signal wire by the fan relay does my check engine light will turn on? What will happen on my temp gauge if I unplug my old harness? Tnx.
 
Does anyone knows where exactly the cooling fan sensor for this year?
There is no " cooling fan " sensor ;
the fans are electronically controlled by the ECM from the engine temp reading it gets from the coolant temp sensor (CTS ) located in the water pump

The single wire unit in the pass side head as you correctly state is for the temp gauge only.

You have to remove the blank plug in the drv side head (good luck ) and install the new fan switch in that location
 
By unplugging the old fan sensor harness and connect the new harness
Your year doesn't have a fan sensor to unplug

What will happen on my temp gauge if I unplug my old harness?
You don't touch the temp gauge wiring

does my check engine light will turn on?
In some years it does ( '96 IIRC ) because the PCM is seeing the fan run ( from the new switch ) without the PCM telling it to run
 
MIKE74

Can you give us the kit number and where you got it. I think you're misreading the directions.

DON'T take the stock sensor or disconnect it. It is tied to the ECM (computer) and effects more than just the fan.

I believe the kit you have is a supplemental sensor that ONLY turns the fan on and off.

Chuck M
 
Sensor

I bought the kit from Eklers and spoke to thier tech support and told me that the cooling fan sensor for that year in on the passenger side between 6&8 spark plug but upon reading to all the replies, that sensor is for the temp guage and now I will check if there is any plug on the driver side by the cylinder head so I can install my new sensor. Kit # is 40416. Tnx.
 
Most people have problems getting the plug out of the head to install the new temperature fan switch.

You could return the fan switch kit and purchase the Tunercat LT1 Tune-2 kit.
The software will allow you to change the fan on off temps and allow you to reflash your PCM.

Cost is around $160.00. The software will also allow you to modify a lot of the engine tuning parameters.

Here's the link for the TunerCat kit.

LT1 Tuning Kits

The fan kit you purchased will set a PCM code but the Malfunction Indicator light won't come on.
 
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A 94 Corvette with the LT1 (VIN P) engine has no sensor or switch which directly controls the cooling fans.

Both fans are controlled by the ECM though two cooling fan relays. The ECM relies on the ECT sensor and the HVAC pressure sensor along with its programming to set fan-on strategy. The engine coolant temperature sensor is in the water pump and the HVAC pressure sensor is in the A/C evaporator line.

Eckler's tech support are morons if they are telling you a 94 LT1 has a "fan sensor" or a fan switch" installed in one of the heads. There are no sensors in either head of a 92-96 LT1. In fact their sales staff are morons for selling you such a piece of crap of an aftermarket product.

What Eckler's "kit" does is modify the cooling system for simple coolant temperature control of the fans. Installation of that kit requires you disable the ECM control of the fans, install an additional temperature switch in the cooling system, then bastardize your cooling fan wiring harness.

Worse yet, installation of this kit disables the ability of the ECM to control the cooling fans when A/C is running. It, also, disables independent control of the two fans and has both fans running whenever the switch closes. Finally, it disables the ECM's ability to request fan-on as a protective measure when certain ECM fault codes are set.

If you insist on installing this kit, you have to read the poorly-written instructions carefully to understand that to make it work with an LT1, you must install the kit's coolant switch into one of the heads, after you, first, remove one of the plugs GM put in the heads using a tool you have to make. Then you have to rewire the fan relays such that this switch, rather than the ECM, controls the two fan relays.

I suggest you send the kit back to Eckler's and get ask for a refund.

Then, take advice "ecss" offers and purchase TunerCat's LT1 kit. It will allow you to reprogram the ECM's fan-on strategy but preserve the ability of the HVAC to request the cooling fans, preserve independent operation of the two fans and preserve the ability of the ECM to command the fans on when certain DTCs set.

Then, what I'd do is: verify the thermostat is a 180°F unit. If it's not, purchase a Stant 45218 from CAC sponsor Rockauto.com and install it. Finally, using TunerCat, program the following fan-on/off numbers into the cal. as a starting point:

Fan 1 on at 200 and off at 192
Fan 2 on at 212 and off at 200

Also, with C4s, there are a couple of other key cooling service procedures you should perform.

1) Remove the top of the cooling stack and inspect the upper part of the HVAC condenser for debris restricting airflow though the HVAC and the radiator. Then inspect space between the HVAC condenser and the radiator for debris. Remove any debris blocking airflow.

2) Inspect and, if necessary test, your coolant pressure cap. If it's bad, replace it with one from CAC sponsor, Rockauto.com

3) To properly cool a C4 MUST have its stock, front air dam. Make sure the front air dam is in place and in good condition. If it's not, you can get a replacement from CAC sponsor, Zip Products.

4) Change your coolant if it hasn't been done in the last three years or 36,000 miles.

5) Inspect all your coolant hoses and replace as necessary.

Good luck, my fellow Corvetter!
 
Sensor

Thanks for the info Hib. I will look onto the tuning kits but their website has no contact or company # at all. Tnx.
 
TunerCat's been around for over 15 years. They give basic support for their products but
of course don't offer step by step procedures on how to tune your vehicle.

They also sell the Datamaster software that allows you to monitor the engine parameters
in real time and play them back. You can download a free trial version for demo purpose.

If you just want to get the fan temps changed, there are companies who will change the fan on and off temps. By the time you ship your PCM to them and back and pay for their service, you could purchase the Tuner Cat kit for the same cost.

Here's the link for TunerCat.

TunerCat

E-mail address is tc@tunercat.com
They usually respond within a day.
 
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I have not used TunerCat myself, because I've never had to calibrate a 94 or 95 LT1, but for those platforms, because they were part of GM's so called "early-rollout" of OBDII, TunerCat is probably the only show in town as far as DIY calibration.

TunerCat is only an editing app and cal work beyond the very basics, such as setting the fan strategy, disabling skip shift on a manual or setting shift points on an automatic, is not going to be possible without a data logger. Datamaster, a logging app the TunerCap people sell, is a good choice.

Lastly, if you decide to take your DIY calibration work into tuning the air:fuel at WOT you must install an auxilary wide-band O2 sensor in the exhaust and buy a wideband controller then use a laptop loaded with display software to see the wideband O2 data. You cannot tune the engine when it's in power enrichment with the stock narrow band sensors the ECM uses for closed-loop fuel control. I use the Innovate Motorsports LC-1 wideband kit. Summit Racing sells it.

Good luck Fellow Corvetter!
 

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