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Discussion Starter #1
I've been spending time laying out my Painless wiring harness for my '55. I have a TPI engine and 700R4 transmission from a 1985 IROC. In the instructions it states that if I am using the lock-up circuit I am going to need a brake switch that is CLOSED (electrically connected) when the brakes are NOT applied and OPENED (NOT electrically connected) when the brakes ARE being applied. This is opposite of a standard brake light switch. Now, I don't claim to be brilliant, and I can follow directions well, but this is my first wiring job that includes a computer. So, what would be a brake switch I can use?

Mike
 

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Discussion Starter #4
Thanks, guys. Wiring is always a challenge for me, but I have been successful RESTORING cars with basic wiring needs. I maybe should have farmed this part of my build to an expert but will get through it with the help of the forum.

Mike
 

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For my 700r4 I simply went simple and avoided all switches. There's no need for a brake switch at all if you use a hydraulic pressure switch. Simply take a keyed power wire and run it to the pressure switch, and then from pressure switch to terminal "A" of the connector, and from "D" to ground. The Superior Solutions pressure switch closes on pressure rise to lock the converter as rpm's rise. Then unlocks as you let off the gas and rpm's slow. So no chance the converter will lock up too soon.
And they're only $37 for the kit., and takes less than 30 minutes to install.

 

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So for the SLS-159 is one set of terminals normally open and the other closed?
Correct the forward set is normally open and the rear set is normally closed when the button is in the depressed ( brake off) position
 

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So for the SLS-159 is one set of terminals normally open and the other closed?
Yes, a switch for a car with cruise control will have 1 N/O and 1 N/C contact. Since the switch is pushed in when installed with the pedal at rest, it will read the opposite when it's held in your hand with the button out.
 

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Since your stuff is from an 85 Iroc, consider a brake switch from an 85 Iroc. It will fit and work just fine.
 

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There are any number of identical dual contact switches, and all of them like this for GM cars will interchange. All have one set of NO, and one set of NC contacts. Painless lists this one at Summit also.
Summit Racing Part Number:PRF-80176
$14.

And they'll all fit in place of the stock brake light switch.
 

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Discussion Starter #13
For my 700r4 I simply went simple and avoided all switches. There's no need for a brake switch at all if you use a hydraulic pressure switch. Simply take a keyed power wire and run it to the pressure switch, and then from pressure switch to terminal "A" of the connector, and from "D" to ground. The Superior Solutions pressure switch closes on pressure rise to lock the converter as rpm's rise. Then unlocks as you let off the gas and rpm's slow. So no chance the converter will lock up too soon.
And they're only $37 for the kit., and takes less than 30 minutes to install.

This sounds like a viable option as well. I like the concept...something I definitely wouldn't have thought of considering had you not presented it, only because this type of "customizing" is new to me. Almost like sitting in front of a computer for the first time years ago and someone saying "just mess around and see what you can do!" and feeling your eyes glaze over! I will dig into this option and take into consideration. Would this eliminate the need for a lock-up kit? I'll read up and see what other questions I may have.

Mike
 

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The hydraulic switch is the means to lock and unlock the converter, but unlike a brake switch it doesn't allow lockup until the pressure is high enough to close the switch. And then it only ties into 4th gear, so lock up wont happen in 1-2-3 gears. So it does the job without needing the brake switch.
Some people use both the hydraulic switch and the brake switch together, and wire them in series so either will close or open the circuit. Seems redundant to me, so I simply use a toggle switch as a main power feed (which stays on at all times) and the hydraulic switch. Works great so far, and no reason to use a brake switch for my needs.
 

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Correct the forward set is normally open and the rear set is normally closed when the button is in the depressed ( brake off) position
So can one double up on the forward set (running brake lights and neutral safety switch) and lockup on the rear (which I believe is to ground)? Don't know what the current draws might be - will the switch handle it?
 

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I wouldn't use the same contacts to serve two functions. It can create a feedback situation where your switch could allow the car to start in gear, or lockup the converter when you didn't want it to lock up. The neutral safety switch is a completely different component, so I'd leave it on the other connector operated off the steering column linkage.
 

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So can one double up on the forward set (running brake lights and neutral safety switch) and lockup on the rear (which I believe is to ground)? Don't know what the current draws might be - will the switch handle it?
The lock-up requires 12 volts to the switch and out of the switch to the 700R4 plug. It opens the circuit to drop it out of lock-up. It's a good idea to use a separate fuse for the lock-up to make trouble shooting easier. If the 2 switches use the same source (fuse) it gets complicated if the fuse blows.
 

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Discussion Starter #19
Jeez....why couldn't one of you guys live down the block from me???!!!!! I would love to hang out in the background just to observe and learn.

Mike
 

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Jeez....why couldn't one of you guys live down the block from me???!!!!! I would love to hang out in the background just to observe and learn.

Mike
I had to learn this 700r4 stuff just recently myself Mike. Never had a 700r4 before, and never dealt with the lockup converters, or how to wire them. I did have a nice long chat with a tech at Superior Solutions after I got their hydraulic pressure switch, as there was no diagram showing which two wires to connect the switch to. He was extremely helpful, but I still had questions. So I spent hours in the internet trying to learn all I could about the 700r4 and wiring the lockup converter.
Glad I did, as mine works great, and I love the 700r4's low first gear launch, and OD 4th gear for freeway cruising!
 
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