I am at the end of my witts on this speedo problem. I still cannot get it to work. Is there something that has to be grounded? Here is where I am at. I took out the Buffer Box Completely. I tried the tan/brown wire that goes to the speedo and it didnt work. After that I went staight to the source and removed my cluster splicing directly into the tan wire that goes to the speedo on the quage connectors. Still nothing. Is there something that has to be grounded from where i removed the buffer box or something else. I even tried a differnt cluster just to make sure it isnt the speedo thats bad but still nothing. Any Ideas? This is the last obstacle i have to get everything working the way it should.

Oh, This is a Howell harness with an imput wire for the speedo labeled. I am waiting on a response from them as well.

 

It doesn't work because the T56 VSS outputs 40,000 ish pulses per mile where as the 3rd gen ones were 4000, ppm.

best thing to get is a dakota digital box or look into seeing if the LS1 puter has a output for the speedo and use that. From what I remember reading, GM still used the 4000 ppm for the speedos.

I could be wrong about the last part.

 

The vss output wire from the PCM should be connected to the wire going to the speedo, not the one from the VSS.

 

Hmm, from what i have read the the ls1 and 3rd gen have the same pulse rate. You only need the dakota digital for the lt1 swap.
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Yeah, The wire labeled speedo from the harness is going straigh to the wire that goes to the speedo. Its getting nothing. I'm just wondering if there is something that has to be grounded. I even swapped clusters out in case the speedo was bad and it still doesnt work...............jt

 

Your car is an RS, I am assuming it was originally a TBI car. Did you remove the VSS buffer under your dash and jump the wire coming from the VSS to the one that goes to the speedo. The circuit can't complete itself through the buffer and is open without it.

 

Hmm, I'll take a look at it today. I did remove the box completely though..........jt

 

I converted a 91 RS from TBI to TPI and I had this problem. I jumped two wires together and the speedo started working. I found the wire colors on this site.