ninetyone

iTrader: (2)

I have a 91 Pontiac firebird. Originally this car was a 5.0 TBI. It is now a 5.7 TPI car. I bought the car that way. However, the speedometer on this car never worked since i bought it. The odometer works just fine though. I looked behind my speedometer and i found no cable. I am assuming it must be electronic then. However, on the transmission itself , there appears to be a cable. There are two cables connected to this transmission. The other cable i am assuming is the kickdown cable. I am aware that these cars use a vss system. My question is this: How can i test to see which components are bad? Is it my vss unit that is bad? If it were vss then my odometer would not work either ,right? Any input would be a great help!

juansupreme

Dude, Ur in luck.
I just went through the mothjer of all troubleshooting the Fr33kin Speedometer.
All I know is that the transmission sends data to the 4 out Buffer (yellow) box. The yellow box takes the signal from the trannys VSS in the DRVR side tail of tranny(Plug) and turns data to signal which is used for speedo, cruise control and ECM.

That Sounds Easy right?
Well in case you check all electronics in car and replace or just verify that they are 90%.
You may need to jack-up rear of car and pull out the VSS sending unit. Only 10 mm bolt and lots of tranny fluid, after the drain look at VSS unit and check gear, its plastic it wears out over time. if it a little worn replace it, go here(http://www.redrider.us/Speedometer_Gears.htm), count the teeth and order same color, no one else carries it any more, AMACO $2000, diy $11 plus shipping for a 2 once plastic wheel. HA! I had an expert at a auto parts store that sweared that I had a speedo cable, cause he had 3 of these cars and he knows about transmission. Ha! Even when I tried to return the cable, he insisted that I'm (lectric speedo on 86 TA) wrong. well I just kept on diggin aroud, got the service manual for the 1986 thirgen(get the book, it's like the car bible. Amen) checked the speedo electric schematic, and there is is. VSS on tranny to VSS buffer box to speedometer. pulled out the VSS and whala, very worn driven gear (red 37 teeth) Dam!!! I feel like I just hit a bases loaded home run. I won't fix anyones car, I only fix my cars, 86 TA, 00 Expedition. after paying $600 for a tuneup, I vowed not to get suckered again. Thanks to service manuals and the internet. I keep all my money and learn a couple of knew things and sometimes, not to do that again

AtlantaTA

iTrader: (3)

@ninetyone,
Did you end up fixing this issue?

ramski9604

Hey guys just wondering if anyone got the issue resolved I just recently got a 83 firebird trans am with the 305 cross fire with the 700r4 my Speedo and odometer aren’t working read the thread and saw that the vehicle speed sensor could be a culprit. With that has anyone tried the summit racing one?

stew'86MCSS396

Not sure if this is the appropriate thread you should be piggy backing on as later years are setup different. Someone correct me if I'm wrong, I'm purdy sure '83 would have a drive/driven gear setup that spins a cable that goes to the back of the speedometer. On the back of the speedometer, you would find a 2k ppm sensor that goes to a buffer that talks to the ecm. I would get under the car and double check. Chances are the teeth on one of the gears have sheared off.
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Edwardgp

Yes my 83 Camaro is cable driven speedo