1986 Trans Am Motor Swap from a 305 carb to a 350 carb. the camshaft was done and the ignition was swapped out. no more electrical ignition.

So, this is my third post to try to find some help with this issue I have with my speedometer and still I can't figure out how to get this speedometer to work. Now the vss is fine wires are fine and buffer box is fine all wires hooked up. The only life i get from the speedometer is if i take a grounded wire and spend a pluse signal manually to the speedometer head. I tap the speedometer head wire (green and black) and the odometer and speedometer will move. I don't know what happening or how to get the speedometer to work all the time. Now I have wires in the engine bay that are cut. the person i bought the car from someone and they cut the wires they are a bunch of wires that come out of the ecm. From what I know is you do not need the computer because of the buffer box. the 2 brown wires on the vss buffer go to the computer, but aren't needed.

I need help because i've done all i can am i missing something to hook up the wiring is good i've gone through every wire but it seems no pulse signal is being sent to the speedometer head. If anyone know how to get this thing to work or if im missing something.

The speedometer worked before the camshaft was changed and the ignition changed I asked the guy who I bought it from who did the cam and ignition. Does that have something to do with the speedometer.

 

Have you tried the speedometer cable? Check it out. Check to see if it became loose behind the Instrument cluster and check the connection on the tranny.

 

No it's an electronic speedometer it has a vss buffer box and the connection from the tranny is fine i followed the wires all the way up to the box and the speedo head wire to the back of the gauges

 

I think you have the same problem I do in that somehow the brown wire that goes to the ECM needs to have a 12V signal on it. My 91 harness is supposed to have a signal wire going straight to the speedo head, and does, but it doesn't DO anything, so I have reinstalled my buffer box and still get nothing ?

 

I got my speedometer finally to work i found the wires from the transmission were cut thanks to the guy I bought it from so i reconnected the wires and speedometer started to work and now all of a sudden its no longer working, so i played around again and now i have an eractic speedometer where it will bounce around

 

Try soldering the wires together to get a solid connection. Also due to the fact that the speedometer was, shall I say,,,,asleep,,,, maby the VSS probably just gave out. This is my best advice to give. Let me know what happens. Good luck.

 

Did you figure it out yet? I had to remove my 91 harness, but with the car being down (alt burned up AGAIN ), I'd like to get it back in there and working. I've tried everything I could think of, even checking the resistances between the VSS and the buffer box (but not between the box and the cluster or C207 and the cluster, with the VSS signal piggybacked off of the ECM harness), and still got nothing, and was hoping you might be able to shed some light on this.