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Lets start inside the transmission ...
There are 2 styles of solenoids used in the 700R4.
first is a 1 wire self grounding unit that only requires positive (12v) feed to it.
The other is a 2 wire unit that requires a ground and a positive feed.
Either 1 or 2 wire will work but changes what pressure switch is required.
There are 4 different pressure switches used in 700R4s & there might be as many as 4 in the valve body.
For this wiring you will need a NO (normally open) pressure switch.
To test if a pressure switch is NO use an ohm meter ).
On single post (self grounding) unit touch one lead to the base and the other to the button connector; if there is no resistance then it is a NC switch but if there is resistance then it is a NO switch.
For a 2 post unit instead of connecting one meter lead to the base connect one to each button connector.
Now that that's covered you need to choose if you are going to use a 1 wire or 2 wire solenoid (I just stick with what's already in the 700R4 I'm working on to simplify things)
If you're using a 2 wire solenoid you will need a single post NO pressure switch (if you choose to order new GM part # 8642473 or 8627332).
If you're using a 1 wire solenoid you will need a 2 post NO pressure switch (if you choose to order new GM part # 8643710).
Next I'm going to cover what you will need outside the transmission.
At this point it doesn't matter which way you picked for wiring inside the transmission because this will be the same either way.
Start with a switched 12v source (key on hot) then hook up an inline fuse (10-15amp).
Next hook the fused wire to a brake interrupter switch (used for cutting power to cruise control when brake is pressed) this step can be a bit annoying as not all vehicles have this to start with (my S10 has it built into the brake light switch even tho it never had cruise). If you have cruise (or at least the wires under the hood) in your vehicle you are lucky because you can test and find the switched power wire under the hood and tap into it adding the inline fuse at this point. If you had to add the brake switch run a wire to under the hood from it.
Next you will need a low vacuum switch GM # 14032087 or 14014519 (this will cut the power feed if vacuum is too low like when under heavy acceleration). Myself I get them from the junkyard (found on early 80s full sized trucks, subs & vans for the lockup normally mounted by the brake booster) but you can also order aftermarket units that are adjustable if you have a cammed engine with low vacuum. You then need to run manifold vacuum to the switch.
Finally you will hook the wire from the vacuum switch to the transmission pigtail. Be sure that the wire is matched to the correct connector in the transmission.
You also could replace the 4 plug connector for a single-pin TH400 kick-down connector GM # 24205373 (this seems silly to me but is a bit less bulk).
Now back inside the transmission...
Install the NO pressure switch into the 4th gear pressure port.
Now be sure the positive wire from the connector is hooked to the wire that will feed the solenoid.
For 1 wire solenoid / 2 post pressure switch connect the feed wire to one of the button connectors on the pressure switch; then run a wire from the other button connector to the solenoid wire.
For 2 wire solenoid / single post pressure switch hook the black wire from the solenoid to the pressure switch connection. Then hook the red (may be discolored) wire from the solenoid to the correct wire to connect to the positive feed to the 4 plug connector.
At this point snip any extra wires from the connector both inside and out of the transmission. If you wish to remove any extra pressure switches you can and replace them with 1/8" pipe plugs.
Now here's pictures to show how simple the wiring is because I know just reading the instructions can sound complicated.
Me speaking now.
Here is the link - this guy did a
real nice write-up:
http://www.s10planet.com/forum/showthread.php?t=31223
