85f-bird

Quick questoin (probably even a stupid one...here it is) when i need to see my computer codes, i ground the ALDL terminal (second right IIRC, to far right (ground) when i do this i use a paperclip to jump between one and the other...the Question. If i go from the Top Left (TCC) to the Top Right (Ground) will it give the same effect...just curious if the paperclip method will work for the Torque Converter clutch to lock it up, as the wire must be grounded......would this be the same as an on off switch? thanks in advance.

TechSmurf

I don't recall if you ground the TCC or give it +12v... but I'm pretty sure you can search up this info on the Transmission board using the terms TCC and ALDL

Trickster

You don't give the TCC any voltage at all. The proper way to test it is to take a test light and with the key in the "ON" position. Put the probe in pin "F" of the ALDL (top row on the left) and ground it somewhere (car frame or pin "A" of the ALDL. Light should come on and TCC is engaged, press brake pedal and light will go off and TCC is disengaged. I have posted the info from the service manual on this for IrocNoz and several others on the board.

85f-bird

sorry, might not have been clear on what i was trying to do. The purpose of installing an on off switch is to lock the torque convertor manually. I've done the test of the TCC circuit (atleast i think i have) i've plugged the light in, grounded it, got a bright bulb, hit the brake, bulb went away...apparently, the light is wires are good, and the brake switch is good, leaving the culprit at the TCC selenoid...my Q, for testing the selenoid (as i've done an on/off switch one wire was to terminal F, other was terminal A, and had no result...which leads me to believe that the stupid thing went bye-bye thousands of miles ago (and i never noticed)) So, does using a paperclip between terminals A and F give the same effect as the on/off switch w/ ground? That's the Question. If that's the case, it'll make it easier to test as i leave the shop on weds. after having the new piece installed, i'll be able to find out if everythings good to go w/o having to wire up the switch atleast during that day, and i can finish it up later that night.

TechSmurf

Actually, if a test light is the way of testing it, that means +12v needs to be supplied to the pin to actuate it. Grounding that terminal directly will create a short and blow fuses or damage the ECU.

TomP

85fbird, yes, connecting the upper-left-most ALDL pin (F) with the upper-right-most ALDL pin (A) will put your torque convertor into lockup.

Pin A (upper-right-most pin) of the ALDL is ground.

So if you connect either a switch between PIN F and chassis ground, or PIN F and PIN A, you're doing the same thing.

My brake switch is bad; my brake lights work, but the TCC is super-intermittant. It's been that way for a year or so. When I'm crusing, if I tap the side of the brake pedal with the side of my left foot, the TCC engages- and as soon as I hit a bump, it disengages. So one of these days I'll fix it

TechSmurf

TomP, Trickster, you really need to settle this so we know what's going on.. If it's a test light port, it can't be a ground-to-activate.

Apeiron

Connecting the test light between pins A and F is proscribed for some tests in the service manual, however the meaning of the light changes depending on the test.

The first test is to connect the light between pins A and F to test for +12v to the TCC. The light turning on indicates that it is, since the light is connected across the voltage between pin F on the ALDL (which it gets through the ungrounded TCC solenoid) and pin A, which is grounded.

The second test verifies that the ECM is applying ground to the TCC solenoid to lock it. The vehicle is road tested, or tested on a lift, and when the ECM commands the TCC to lock by grounding the TCC signal, the light goes off, since it is now connected across two grounds.

The light also goes off during either test if the brake is applied, since this opens the brake switch and removes +12v from the TCC solenoid.