'84 Trans Am G - Speedometer Problem, Need Help Identifying Part

[Fit4Demolition]

i've been to a few places trying to find out what this part is and no one has a clue. this part is basically down by the transmission and driveshaft and has about a six inch speedometer cable connecting it to the speedometer gears behind the transmission, as seen in the first pic, and a longer speedometer cable connecting it to the speedometer gauge, as seen in the second pic. it also has two electrical wires coming off the side and following the longer speedometer cable into the cabin.

the problem is my speedometer gauge and the odometer doesn't work and the computer isnt picking up any speed signal, causing it to burn very rich as the computer thinks the car is at a stand still and is being reved up. the speedometer cables aren't broken, as that was the first thing i tested. first i disconnected the short cable from the back of the transmission and spun that seeing if the speedometer would move, it didn't. then i disconnected the long speedometer cable from the unknown part and spun that and the speedometer worked so i know what ever the unknown part is is causing the problem.

i asked a local mechanic and he told me to see if an auto parts store could match my pics up with one of their parts catalogs. i've been to three different auto parts stores and they have no clue what it is, except that it sounds like the speed sensor, but the speed sensor their computer shows looks nothing like this part. my dad told me my best bet is to go to a pontiac dealership and have them take a look at it, but i know they would probably charge me a fortune just for a consultation.

if anyone knows what this part is or has had the same problem i do, please let me know.

my car also has cruise control, which i am not sure was factory installed. one of my first thoughts was that this part was some kind of aftermarket cruise control part. but i dont really think that is what the part is.

[Morley]

That is indeed a speed sensor probably for an aftermarket cruise control. For now remove it and hook the speedo cable to the trans. You are doing more than you know by not having the speedo working. The transmission's lock up torque converter isn't working either (if it is an auto trans). The factory cruise control and ECM use a speed sensor mounted on the back of the speedometer head. The ECM uses the signal to tell the converter when to lock up. Not sure if it uses it for fueling calculations for the computer controlled carb though.
After removing it you need to track down the other parts for the cruise (servo) and see if the mfg's name & model number are on it. From there you should be able to contact them about replacement parts.

[Fit4Demolition]

Originally Posted by Morley

That is indeed a speed sensor probably for an aftermarket cruise control. For now remove it and hook the speedo cable to the trans. You are doing more than you know by not having the speedo working. The transmission's lock up torque converter isn't working either (if it is an auto trans). The factory cruise control and ECM use a speed sensor mounted on the back of the speedometer head. The ECM uses the signal to tell the converter when to lock up. Not sure if it uses it for fueling calculations for the computer controlled carb though.
After removing it you need to track down the other parts for the cruise (servo) and see if the mfg's name & model number are on it. From there you should be able to contact them about replacement parts.

cool thanks. whats funny is the turn signal lever with the cruise control is also broken on my car. if the cruise control is an aftermarket addition would it be possible for me to get rid of it and go without cruise control?

[Fit4Demolition]

i actually took a better look at the problem part, and its actually not broken. i could see that the other end spun when i spun the speedo cable on the other side. i looked at the speedo cable that runs up to the dash and the end that goes into the part doesnt have a cable end on there for some reason. i have no idea where i went but without that the cable wont spin so i tried to put a cable end on that i got a while ago with a new speedo cable that i never installed and the part of the cable end that went over the cable broke because the little crimper tool they give you in the same package sucks ass. so now once i get a new cable end and something better to crimp it with, my speedometer should work fine. hopefully.

now if only my goddamn accelerator pump didnt go bad yesterday i would be in decent shape