The Plastic Lizard

I've been doing an ls engine swap in my 84.

I have a 4l60e and had a tailshaft adapter so it would match up. The VSS is connected to the LS ECM and the ECM has a 1 wire output for the speedo.

However, as many of you know...in the old days the VSS was connected directly to the digital speedo, and then it had an output to the c4 computer. I believe it is circuit 400 and 401 going into the dash.

Does anyone know in this instance how to wire it up? I'd rather not get the answer of "buy a different speedometer"

Cliff Harris

The signals are not compatible. The later units are electronic and the earlier ones are just an AC motor hooked up as a generator. I'm pretty sure the number of pulses per mile changed also. There are converters available for rear axle gear ratio changes that can make the conversion.

Trmccarty

I think this will do the job for you. http://www.dakotadigital.com/index.c...rod/prd126.htm
I used one when I changed to 4:10 gears, was easy to wire up and works great.

hcbph

I don't know the details as this was done prior to my purchasing the car but my 86 had a Tremec transplant done to it and there's a DakotaDigital converter in it to convert the signal to work with the speedometer. I've found the doc on it and it really doesn't look that difficult. Hardest part looks to be how to get it calibrated properly.

DanZ51

Converted to a T56 for my '86. Used the Dakota Digital SGI-5 signal converter. Same deal for you, I would guess.

http://forums.corvetteforum.com/c4-t...he-speedo.html

SilverOverdrives

This is exactly what we use in our 5 speed kits.

rlane5

I used a Dakota Digital SGI-5 signal converter also with no issue. You need to have the VSS connected to the ECM, and the output signal coming from the ECM to the SGI-5, and the SGI- output goes to the wires that was connected to the original wires that came from the VSS which goes to the speedometer.
Randy