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Discussion Starter · #1 ·
My engine isn't in a Camaro, it's in a Lotus 7 type kit car and the cooling system is completely custom, replaced the pump with an inline electric pump with a separate controller for the pump and fan. The controller takes input from a temp sensor and pulses the electric pump as needed to maintain a preset temp. However now I get a permanent troublecode for the fan since the PCM is no longer controlling it. Any way to program this out or anyone have a creative way of tricking the PCM into thinking the FAN is still there? I guess if I plug the PCM into a relay that goes no where for fan that would theoretically work, not as elegant as disabling fan control in the PCM but I suspect that isn't possible.



Paul
 

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You can eliminate most every item in the pcm. Of course some things are needed to run the engine. You can disable the fan trouble code. Or you can set the fan turn on temperature so high that pcm will never see that high of a temp and try to turn fan on.

You can fool the pcm into thinking there is a fan there by wiring in the relays and installing 2 very tiny 12 volt fans hooked to the system. You know the kind of fan a pc uses. Since pcm doesn't measure the load on the electrical system, just the fact there are fans running, should do the trick, if you wish to go that route.

For tuning, you can download tunercat's obd1 tuner. It will change any and all info in the pcm. I do, however, suggest you read up on pcm programing before attempting to tune.

PM me with your e-mail address and I'll send you what pcm tuning info I have, plus as an added no cost bonus, "sensor readings and what they mean".
 

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You can fool the pcm into thinking there is a fan there by wiring in the relays and installing 2 very tiny 12 volt fans hooked to the system. You know the kind of fan a pc uses.
I don't think the PCM monitors the load other than current sensing the relay coil. That's grounded by the PCM. I think just having the relay coil connected would be fine.

Mitch
 
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Discussion Starter · #4 ·
You can eliminate most every item in the pcm. Of course some things are needed to run the engine. You can disable the fan trouble code. Or you can set the fan turn on temperature so high that pcm will never see that high of a temp and try to turn fan on.

You can fool the pcm into thinking there is a fan there by wiring in the relays and installing 2 very tiny 12 volt fans hooked to the system. You know the kind of fan a pc uses. Since pcm doesn't measure the load on the electrical system, just the fact there are fans running, should do the trick, if you wish to go that route.

For tuning, you can download tunercat's obd1 tuner. It will change any and all info in the pcm. I do, however, suggest you read up on pcm programing before attempting to tune.

PM me with your e-mail address and I'll send you what pcm tuning info I have, plus as an added no cost bonus, "sensor readings and what they mean".
I don't think the actual fans are needed, I think the relay would suffice, I doubt the PCM knows there is actual load.

That said if I can simply tell the car to ignore error code 77 that's much more elegant.

PM sent.
 

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+2 w/previous post ....you have 3 choices.. the PCM drives pin A11 ( Fan 1 , or low speed) to 0V to activate fan relay #1. Now when it is not commanding the fan on it expects to see +12 volts on that pin. The +12 comes from the fan fuse , through the relay coil, back to pin A11. You can add a dummy relay w/+12 v ignition on one side of the relay coil and the other side of the relay coil to pin A11. Or you can add a 10K ohm, minimum 1/4 watt resistor from +12 v ignition to PCM pin A11. OR If you have tuning s/w you can remove the X in DTC 77 and turn off the error.
 
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Discussion Starter · #7 ·
+2 w/previous post ....you have 3 choices.. the PCM drives pin A11 ( Fan 1 , or low speed) to 0V to activate fan relay #1. Now when it is not commanding the fan on it expects to see +12 volts on that pin. The +12 comes from the fan fuse , through the relay coil, back to pin A11. You can add a dummy relay w/+12 v ignition on one side of the relay coil and the other side of the relay coil to pin A11. Or you can add a 10K ohm, minimum 1/4 watt resistor from +12 v ignition to PCM pin A11. OR If you have tuning s/w you can remove the X in DTC 77 and turn off the error.
Yeah, I'm just going to disable DTC 77, it's the clean way to do it.

Paul
 
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