Topic: 1980 T/A transducer vacuum for cruise control

[Dinero]

Ignition was on

[b_hill_86]

Ok those are good things so far then I think. The two switches with the plungers, one is the electric switch i mentioned that activates the brake lights and disengages the cruise. You could test that by unplugging the connector on that switch for the cruise control which should expose two terminals on the switch. Connect your multimeter to the terminals using the ohms setting. There should be continuity (should be a reading) with the pedal not pushed. When you push the brake pedal, you should lose continuity. I think the brake light wires for my 77 are green and red. Yours may be different.

The other switch with the plunger is a vacuum dump valve. Its so when the cruise is engaged, and is pulling vacuum on the servo, when you press your brake the electric switch cuts off power to the transducer and the vacuum dump valve opens and allows the vacuum to escape which allows the throttle to return to the closed position.

[b_hill_86]

I was thinking, while you're there at that switch, you could test to see if youre getting power to the switch. i dont remember what the colors are but one of the terminals on that connector should have 12v with the key on. Put the positive tester lead on one wire on the connector and the negative lead on a good ground and test for voltage. If none, test the other wire.

let me know

[Dinero]

ok, on the brake switch there are 2 terminals, one has a white/orange and the other has a brown, pink and black. which one do I test? the orange/white connector the is one closest to the plunger. the vacuum dump connector where the hose goes to is also stopping the white orange connector from coming off.

[b_hill_86]

White and orange should be for the brake lights. I think the colors of the wires are different between 77 (my car and the manual i have for it) and your 80. Youll have to pull that connector with the brown pink and black off and test each of those for 12v with the key on. I'll try to do some more digging in the meantime and see what i can find. Itll probably be the brown wire if i had to guess. Are you sure there are 3 wires on that plug?

Are you able to post a picture of it by chance?

[Dinero]

BTW, I found the bracket part that holds the threaded part of the switch and the dump switch not holding them in good. they were pushed out so i push both switches up against the bracket. not sure if this was throwing off the adjustment. wish there was a way to test to see if that was the problem without having to drive the car

[Dinero]

actually 2 brown wires, one comes in from the firewall bundled in with the vacuum dump hose, the other brown wire comes from a connector. so those 2 brown wires come together into one wire into one of the spades and then there is the pink wire. so these 3 wires make the 2 wire connector to the switch, that switch looks to be easier to come off to test

[Dinero]

will try to get a good pic. will have to send as attachment

[Dinero]

1st 3 pics are switches and the last is the transducer. hope they show up clear for you Brian. thanks

[Dinero]

2nd pic

[Dinero]

3rd

[Dinero]

transducer itself

[Dinero]

question, what actually grounds the transducer? is the that little thin copper wire?

[Dinero]

so i put the meter to ohm's. put the meter wires on and just got OL, then switch meter wires and get a reading of 0.00. also put a test light to it and got a good light. thanks

[Dinero]

ok, switched meter to V. got a reading of 0.15. also that 3 brown wire that goes into the brake switch comes from the connector that goes to the turn signal lever. that brown wire goes with the blue and green coming from the transducer