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I'm, Ron Burgundy?
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Doing my 5.4 swap soon and curious what is the function of the ccrm. I know it controls the AC and fuel pump relays. I won't be using either. I'll ne running a return fuel system and making my own AC delete. What else, if anything, does the ccrm control
 

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In addition to the fuel pump and AC clutch the CCRM switches power to the PCM, when the ignition key is in the RUN or START position, and switches the low and high speed operation of the engine cooling fan as commanded by the PCM...
 

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I'm, Ron Burgundy?
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Discussion Starter #3
Can i not run my own relays for that?
 

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Can i not run my own relays for that?
Sure...

One issue to be aware of is that the CCRM seems to use a solid-state relay to isolate the PCM from the low-speed fan relay coil. I suspect this is to protect the PCM from any reverse EMF spike that might occur. Here is the wiring diagram:



The diode across the relay coils is a brute force reverse EMF blocker, the solid-state device is probably "just-to-make-damned-sure".

The high-speed fan relay has no such protection, this is likely because when the fan is commanded to run at high-speed it is already running at low-speed, likewise when high-speed operation is turned off the fan remains running at low speed. Both of these conditions would not generate high EMF spikes.
 
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