If you just have to have another output available, you can use one of these TCC Controllers to run the TCC, and then use the old TCC output for some other function.

$189.95

sales@digitalhorsepowerinc.com

I've been Beta testing one for some time now, and it's a kewl little controller.

Unlike everything else to date this one is smart enough to work properly. ie won't hunt in and out of lock up.

 

I don't use lockup. Only in OD

 

The TCC signal would be the ideal signal to run fans. Just have to make it would when 0 mph VSS input.

 

Gotta love old Grumpy, who else continually throws ideas at us that make us think outside the box.

Anyway though, how many outputs and what are they are available for finessed use?

 

No hysterisis so the fans can flicker between on and off.

 

I just has one output.
But, you have TPS, MAP, VSS, 3rd gear, 4th gear, as input options.
Soooo you can turn things on only at heavy loads, or once under way.

 

Sort of off topic but non the less interesting. If you have a 3rd gen with a C3 ecm you have one free output, namely the pin A2 that is meant to drive the A/C compressor. The access to the stuff that turns on the A/C compressor output is also just contained in the portion of the source code that is on the prom (8063/8746), so some how, some way you could turn it on if you could squeeze in a line or two to control it. The ideal way, though, is just to take over the loop that is dedicated to controlling the smog pump, CCP, and EGR. There is alot of junk there that is just for the smog pump. Delete it and it frees up processing time that can be used to control stuff. The only bad thing is that the outputs are commanded to turn off in the event of an overvoltage so if the alternator gives up there will be no fan.

 

So, could this work on the 8746 without the TCC if I wanted to make it do so? I thought about using the TCC stuff, but it seems like it wouldn't get a fan at 0 mph. I really wanted to use the EGR stuff to do it, but it was looking like it wouldn't work without going ROMless and I am really not to that point in all this yet.

 

IMNSHO, the best thing to try with a 8746 is replacing it with a 749. I still don't get why no one seems interested in doing that.

Why won't the EGR run it?. Other then no hysterisis.

 

The EGR won't run it because (I think) there is some stuff that happens to SA and AFR when EGR is active. I also tried it sitting on the driveway and it wanted to turn OFF when the engine got up to the temp I had specified for it to turn ON. I didn't even attempt to make it work with the speed constants. I had set the speed constants to turn it ON at 35mph and less and OFF at speeds greater than 55mph. Needless to say, if it didn't work sitting in the driveway, I doubt I could rely on it driving the vehicle 22 miles to work.
What's all this about swapping it to a 749? Educate me...please...

 

The easiest way is to use the MCU outputs. Simple '1' for on and '0' for off. The egr output is more complicated, you dont have access to do the actual output, and when activated it affects alot of stuff. I stand corrected, though. The loop (again, 8063/8746) that controls the mcu that has the a/c output checks to see if the bit for a/c drive is selected but there are no provisions to actually set the bit to cause it to come on, so the default is for it to always be off. So, you have no choice but to go romless if you where to use the C3 and have actual fan control. I did write some proto-code up to control a fan and it works on the bench but I still have yet to add the finishing touches to my $4D source code or convert my ecm over so I havnt tried it in the car yet.

 

What masks can be run? Just the $58 if its being used with a tbi application?

 

It has the injector drives to be able to handle the TBI injectors. Then just rewire as necessay.

Gives you the fast ALDL etc......

 

8D or 58.
You lose some functionality with 8D, a quick search will bring up what. Nothing important to the running of a normal engine.......

The 58 in one bar mode would be kind of neat since it gives you the better AE functions.

Heck try em both.