My older 700r4 transmission has an unusual internal wiring setup I have discovered. The bottom line is that it cannot be wired so the ecm will know it is in 4th gear. What will be the result of this? Can I still use highway fuel mode later on? Anything else weird to be expected?

Steve

 

Of the ones I've seen the ports are there, and it's a matter of removing the plug (s), and installing the right pressure switches.

Might look at a flow chart, on the 200s the 3rd gear switch stays on in both 3rd and 4th.

Lean cruise while easy on gas, is hard on the engine. You have to run more timing, and with the leaness, and higher timing the oil temp goes up. Which ain't a good thing, LONG term.

 

Grumpy,

Thanks for the reply. I understand what you say about highway fuel and it is not critical for me. I would like to have the option however if I could.

Here's the internal schematic on my tranny:

http://www.700r4.com/tech/tcc/TCCinternalwiring.htm

Since the lockup solenoid is internally grounded, I cant even have the ecm control it without adding an external relay since the ecm pulls the output low to ground the solenoid.

But I've thought and thought about how the 4th gear switch is internally wired and I cant see how to make it ground a signal when in 4th which is what the ecm wants. The switch would ground pin A thru the solenoid but when the ecm locks up the TCC then pin A would go high and the ecm would think its no longer in 4th.

I did consider rewiring inside the transmission but the connector is on top and i dont know if I can access the backside of the connector without disassembling the case.

The easiest thing would be to just forget the 4th gear input to the ecm, but that brings me back to my original question: If I do that would it cause any problems?? I can do whatever I need to do in the BIN.

Any suggestions would be GREAT

Thanks

Steve

 

Painless Wiring sells a kit that will shift to 4th for you and lock up the converter. less heat build up, better mileage. drop the pan, run the wires, your good.

 

Good kit. I had a 700R4 put into my 70 pickup, I had this installed when the tranny was rebuilt. You never have to worry about flipping a switch or anything. The only reason that I did this, is because I didn't have a computer to control it.

The easiest thing to do is install this kit and disable the flag (checkbox) for the TCC lockup on the chip.

 

Thanks, guys...

This is a 55 chevy which I am putting the TPI on. Before, with a carbeurator I just had a switch to lock up the TCC and the brake switch would kick it off. I could go back to that but I really want the computer to control it. Since I first started this thread, I have gone ahead and added a relay which the ecm will control by grounding its coil. This will then put the 12v on the lockup solenoid and I will be in business. Except the ecm wont know when I'm in 4th gear. It looks like in the stock BIN the TCC control uses the same lock and unlock speeds in low gear and high gear so that shouldnt be a problem. I guess I'll cross the next bridge when I get there.

Steve

 

What you want to do is very simple.
You can replace the TCC solenoid with one that has two wires coming off it for about 12 bux.

The 4th gear pressure switch is about 13 dollars.

The wires going to the external connector PLUG ON the bottom so you can just pull them off from the bottom side.

You can wire the 4th gear switch to signal the ECM is in 4th gear.
You can wire the TCC activation solenoid to be controled by the ECM.

With the 4th gear switch closed and the speed parameter matched or exceeded the ECM will lockup the TCC.

Not in 4th gear the ECM will still control the TCC.

I bought a 'high dollar' tranny and it was ALL screwed up (internal wiring).

Edit: It only takes THREE wires to make it all work.
1) 4th gear switch signal to ECM
2) + 12 volts for TCC solenoid + connection
3) - TCC solenoid connection to ECM
I just did this exact same thing to mine.

Pretty simple. Not expensive.
Now I can burn EPROMs to change my TCC lockup.

 

Well, ALLRIGHT Jim!

There's the info I was looking for. THANKS!

Yep, I understand the wiring thing just fine, and I can do all that. One clarification though....Since I dont have the pan off the tranny yet I dont know how it is laid out in there. If I pull the wires off the bottom of the external connector, how do I fish the new wires back in? Do they run in some sort of tube inside there? Maybe the connector comes loose from the outside and you can get hold of the wires there?

Would a transmission shop have the solenoid?

You da man,

Steve

 

Steve,

Theres a little square wire loom 'thingy' in there you can use to route your wires through.

If you order a new solenoid harness from the link I'm going to leave here, it'll come with a new one.

Sounds like you need the TCC solenoid harness, new solenoid and a 4th gear pressure switch.

If you pull the pan first you may find you already have a 4th gear pressure switch. But a new one is just a few dollars.

These folks also have that connector that fits on the side of the case. The wires have spade terminals that plug onto the feedthru connectors on the connector that's just above the shift belcrank.

Might as well get you a new pan gasket and filter, it'll be a good time to change the filter while you're in there.
There's a round orange O-Ring that will likely stick up in the filter inlet bore when you remove the old filter. Be sure and get it out before installing the new filter.

HERE'S THE FOLKS TO GET ALL THIS STUFF FROM.
I got all my stuff from them. You can order right on line. They are very responsive and IMHO GREAT folks to deal with.


GO Here:

http://www.bulkpart.com/