2 wires vs 3 wires

[Ranger-Justice]

I have a 1989 ford ranger 2.9 2wd with no tranny, today I picked up a tranny out of a 91 4.0 and it seems to bolt up right but on of the sensors in the tranny has 3 wires going in and my truck only has two, also it has another sensor that my truck doesn't seem to have. So should stop and not finish putting it in or will it work?

 

[RonD]

Odd that an '89 only has 2 wire trans harness.

Earlier A4LD transmissions had an electric solenoid inside to lock torque converter(TCC), this was computer controlled and requires 2 wires, 12volts and a Ground that the computer controlled to activate solenoid.

Overdrive(OD) shifting was control by a Vacuum solenoid hooked to the engine.

I thought it was '88 when A4LD got added electric solenoid for OD shifting, these would have 3 wires, 12volt and then 1 Ground each for the TCC and OD activation, both computer controlled.

You will need the 3 wire connector for the trans in any case, to keep TCC control.
You could add a switch on the dash to control OD selection, like an "OD" button.
It would just be a ground hooked to the 3rd wire, so 1 wire from that trans pin to dash, an on/off switch hooked to dash ground.

Good diagram here for the connector: http://www.ford-trucks.com/forums/1...e-wiring-help-for-the-t-c-lock-up-switch.html

And as said in this link you don't need the OD lock up, trans will shift into OD on its own, it just won't stay in OD like it should for best MPG, it won't hurt anything though.

And other option would be to get a newer computer with 3 wire harness, but a more expensive option.

Not sure on "other sensor" unless it is located next to shift linkage, if so it is an NSS(neutral safety switch), it would have reverse lights and a pass thru for starter motor activation, so starter would only work in Park or Neutral.

 

[Ranger-Justice]

ok thank you so much for reply has already helped a lot. I guess I don't know what I'm talking about so I took some pictures to explain whats going on. I took a picture of the trans I just got so you can see the two "sensors" I'm guessing that's what they are. The only plug in I do have is 2 wires and plugs in at the back of the tranny. I don't seem to have the plug ins for the two plugs in picture number two

 

[Ranger-Justice]

Well I feel stupid now after reading about the truck some I figured I had to have those wires, like said the guy I bought the truck from took the tranny out, anyways I started following wires around until I found the two plug ins he had bunched them up under the brake master cylinder. So thanks for the help but it was mostly me over looking stuff......SMH