Add PCM fan control to 2002 Tahoe?
Add PCM fan control to 2002 Tahoe? I have a friend that has swapped a 5.3 into a Wagoneer, and would like to use the PCM to control his electric fans, if possible. I'm using the latest "Beta" from HPtuners, and still can't get a signal from the PCM to trigger a relay on the "Blue-42" pin or the "Red-33" pin. I'm assuming that these are the pins to be used, as they are correct for an 02 f-body using the same PCM (with a different OS, obviously).
I've been told everything from "You don't need to do a segment swap", to "A segment swap from an Express Van MIGHT work..."
Does anyone have a definitive solution to this, other than "use an external fan switch sensor"? It would really be nice to have everything controlled by the PCM natively. I've attached the PCM .bin file, just in case.
Thanks in advance for any leads.
I've been told everything from "You don't need to do a segment swap", to "A segment swap from an Express Van MIGHT work..."
Does anyone have a definitive solution to this, other than "use an external fan switch sensor"? It would really be nice to have everything controlled by the PCM natively. I've attached the PCM .bin file, just in case.
Thanks in advance for any leads.
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You need to set the fan switch to 2 fans, turn off the recirculation door, and set the fan values. you don't need to a segment swap, you never did. IIRC HPT added the redic door switch, so you can run both fans, if they didn't you can only run one fan.
Are you running flex fuel? If not I should be able to send you a file as a true Bin file with the fans set up. I don't think I have the flex fuel version of it
Are you running flex fuel? If not I should be able to send you a file as a true Bin file with the fans set up. I don't think I have the flex fuel version of it
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I just looked at your file
Under system
Selete the fan tab
Under fan type Select 2 fans
Fill in the fan values
Then select the AC tab
Under Recirc option select Fan #2
You should be good to go
If you go to the scan setup you shoiuld be able to force the fans on to test them, its been a while since I've used it, but I know it will do it
Under system
Selete the fan tab
Under fan type Select 2 fans
Fill in the fan values
Then select the AC tab
Under Recirc option select Fan #2
You should be good to go
If you go to the scan setup you shoiuld be able to force the fans on to test them, its been a while since I've used it, but I know it will do it
Thanks for the replies. The file I posted is from right after initial start-up of the vehicle. I did try it with fan values set up, but don't recall setting the recirc option. I'll try it all again...hopefully tonight.
No, the vehicle is not running flex-fuel, but it IS a flex engine with the flex injectors....just none of the flex sensors are hooked up. I tried to disable everything that I could find pertaining to flex fuel, and it seems to run perfect. I guess that time will tell?
Thanks for the help....I'll see how it all goes.
No, the vehicle is not running flex-fuel, but it IS a flex engine with the flex injectors....just none of the flex sensors are hooked up. I tried to disable everything that I could find pertaining to flex fuel, and it seems to run perfect. I guess that time will tell?
Thanks for the help....I'll see how it all goes.
Just disable the "fuel composition" sensor codes and on the fuel tab set the stoich fuel ratio to ~14.68 or whatever fuel your running on the entire table. My dad's 05 Sierra is a Flex truck and the fuel composition sensor went bad and cost's around $400 to replace so I just disabled it on his and it's been running fine for over a year! We don't have any e85 station's around here anyway.
I just looked at your file
Under system
Selete the fan tab
Under fan type Select 2 fans
Fill in the fan values
Then select the AC tab
Under Recirc option select Fan #2
You should be good to go
If you go to the scan setup you shoiuld be able to force the fans on to test them, its been a while since I've used it, but I know it will do it
Under system
Selete the fan tab
Under fan type Select 2 fans
Fill in the fan values
Then select the AC tab
Under Recirc option select Fan #2
You should be good to go
If you go to the scan setup you shoiuld be able to force the fans on to test them, its been a while since I've used it, but I know it will do it
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The PCM pins ground the relay coil to turn on the fans. You should have 12 volts going to one side of the relay coil and the other side of the coil going to the PCM pin. Is this how you wired it?
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Verdad Gallardo Correct....but when the PCM pins are constantly at ground, the relays will allways be "on"....correct? That's what is happening. I have not even wired in the relays yet, until I can get the PCM to switch the pins. We've been checking the leads with a DVOM to see what they are doing, and so far...they just stay at ground.
Is there a chance that we're checking the wrong pins? I just assumed that they would be the same as an 02 f-body.
It's not a dry contact output, it's solid state. You are misunderstanding what you see on the meter 
The output is logically low but extremely current limited in "off state". The DMM's input impedance is very high so there is no load on that output and it sees ground. The PCM does this so that it can also monitor the circuit's condition and tell if the relay coil has failed open. Just hook it up to test the calibration changes.
The output is logically low but extremely current limited in "off state". The DMM's input impedance is very high so there is no load on that output and it sees ground. The PCM does this so that it can also monitor the circuit's condition and tell if the relay coil has failed open. Just hook it up to test the calibration changes. It's not a dry contact output, it's solid state. You are misunderstanding what you see on the meter The output is logically low but extremely current limited in "off state". The DMM's input impedance is very high so there is no load on that output and it sees ground. The PCM does this so that it can also monitor the circuit's condition and tell if the relay coil has failed open. Just hook it up to test the calibration changes.
The output is logically low but extremely current limited in "off state". The DMM's input impedance is very high so there is no load on that output and it sees ground. The PCM does this so that it can also monitor the circuit's condition and tell if the relay coil has failed open. Just hook it up to test the calibration changes.Definitely food for thought. Thanks for the explanation. I guess we'll just hook up a couple of relays, and see how it goes. Thanks again.
