1994 CCRM Question

[Rob Liebbe]

There is progress in the new car build. One of the steps is using a running 94 GT with a bent body that I have as a donor for wiring, fuel system, dash, nuts/bolts/etc. In checking that the wiring is ok, I was running the engine at fast idle and noticed that while the engine was getting quite warm by the factory gage, the stock electric radiator fan was not coming on. I've read that the fan relay is in the CCRM and can be bad, some talk about diagnosing by shorting the engine coolant temp sensor on the water heater piping to see if the fan actually works, others jump power straight to the fan, some short a certain wire on the module to ground to bypass the CCRM fan relay. I guess my question is, what else does the CCRM do (seems like fuel and PCM relays are in there)? Can I bypass the fan control portion and run a Hayden sensor/switch unit? Any thoughts are appreciated.

I'll also take any suggestion on what to remove from the factory harness to simplify life (radio, windows, etc.)

Thanks.

[Tilton]

I also read that you could splice into the wiring for either the high speed or low speed fan modes. The number of people who shorted the entire CCRM doing so kept me from trying it.

I ended up cutting the fan pigtail and wiring it up with a manual switch to high speed only. As of now, I am getting 12v from the back of the alternator into a 60amp maxi fuse then into a relay (left over fog light relay) then to ground/signal/high speed fan.

[blk96gt]

Here's the writeup for the manual override fan switch install:
http://www.allfordmustangs.com/Detailed/499.shtml
If the fan relay is already bad, I don't think this method will work, as all it does is complete the circuit with a ground. It's also possible to replace the relay in the CCRM. The best method is to bypass the CCRM completely. I have mine wired with a 70a relay and a 40a fuse. I tried a 25a relay and fuse at first, but ended up melting both of them. With the 70a relay and 40a fuse I never had any issues, and the wires/fuse/relay never even got warm. I only had the high speed wired up.

As for getting rid of all the other crap, give me a call or let me know when you want to strip everything out and I can come give you a hand. I just got done doing that on my car, and, other than PATS, the chassis harness is basically the same for both cars. If all you need are brake lights and some gauges to work, you can get ride of pretty much everything that runs under the dash. You just have to bypass the hazard and turn signal switch, and run the wires from the brake on/off switch to the tail lights. There are also three ignition switch fuses, which you can reduce to one if you plan on getting rid of key tumbler and going with switch panel.

[Rob Liebbe]

Here's the writeup for the manual override fan switch install:
http://www.allfordmustangs.com/Detailed/499.shtml
If the fan relay is already bad, I don't think this method will work, as all it does is complete the circuit with a ground. It's also possible to replace the relay in the CCRM. The best method is to bypass the CCRM completely. I have mine wired with a 70a relay and a 40a fuse. I tried a 25a relay and fuse at first, but ended up melting both of them. With the 70a relay and 40a fuse I never had any issues, and the wires/fuse/relay never even got warm. I only had the high speed wired up.

As for getting rid of all the other crap, give me a call or let me know when you want to strip everything out and I can come give you a hand. I just got done doing that on my car, and, other than PATS, the chassis harness is basically the same for both cars. If all you need are brake lights and some gauges to work, you can get ride of pretty much everything that runs under the dash. You just have to bypass the hazard and turn signal switch, and run the wires from the brake on/off switch to the tail lights. There are also three ignition switch fuses, which you can reduce to one if you plan on getting rid of key tumbler and going with switch panel.

I saw that article on allford. I'm going through this mess because I'm not good with wiring and the Televork <sp> harness for this car is $800-900, 94-95 cars are unique. I know you can use a Painless harness from a 89-93 but that requires some trickery, so I thought I'd go stock for now.

[Wade]

Rob, you already have the PCM, TB, and harness from your fox. Buy a painless (or don't) but use the fox stuff. It will help with parts availability (tiny parts stores in remote areas) in the future, and will simplify the entire mess. No CCRM, no PATS, etc.

[blk96gt]

Isn't there something better about the Fox PCMs performance wise?

[blk96gt]

Well this kind of answers my question. Here are some instructions on converting an sn95 to fox computer. Was this the trickery you were referring to earlier Rob?

http://forums.corral.net/forums/7529858-post7.html

Not sure if the effort is worth the payoff though.

[Tilton]

Isn't there something better about the Fox PCMs performance wise?

I've heard the Fox PCM is RPM based vs the SN95 load based timing curves. Not sure if that is true though.

[Supercharged111]

I don't know about performance, but I do know the SN95 ECMs use the same pinout as a Thunderbird and have some sort of databus that the earlier ones don't. I seem to recall that the Thunderbird ones sucked, but not why and if the SN95 shared that same sucky thing.