gmfanatic92

iTrader: (-2)

I have a 92 gmc blazer which has a small little white DRAC box which controls the speedometer readings I am under the impression the one single VSS wire coming from the LS swap harness/PCM where does this wire splice into on the DRAC box?

http://www.bing.com/images/search?q=...lectedIndex=24


in this diagram would I just splice into the top blue/black cable going to speedo or do I need to go to a differecnt wire. I know that the signal wires coming from the VSS on transmission cannot go directly to the speedometer or drac box unless a certain type of resistor is used in line as they read a different signal from what ive read. so what can I do to get my speedo reading and moving?

gmfanatic92

iTrader: (-2)

so no ideas on this guys?

gofastwclass

iTrader: (2)

From your diagram that appears to be your wire, however I doubt a simple resistor could be used on a sine wave or pulsed signal wire.
What you need to know is what type of signal input is the dash looking for? If it's the same signal type as generated by the PCM, connect the wire and simply calibrate the speed output in the PCM - problem sorted.

If you need a different signal type or pulse rate, try using a Dakota Digital SGI-5c before the speedometer. It's adjustable to nearly any input and output you need. I'm using one for the speedometer on a couple cars and as in input driver to the PCM on another.

71403

The factory speedo is looking for a 2k or 4k ppm vss input, if your PCM is already setup for that just connect it directly to that input on the dash.

The DRAC gets signal directly from the VSS in the trans, no resistors. I've run both the PCM and a DRAC off the same VSS.

gmfanatic92

iTrader: (-2)

ok well im trying to connect speedo without using a Dakota digital box. Others from what I have read connect VSS wire from lsx pcm to a wire located at the DRAC box but im unsure how, which ever way they do it theyre able to make the pcm signal work with the speedo on the truck without a resistor, I just don't know which wire to splice into on the DRAC? I know the threads I had read leave the DRAC connected in line so im guessing the DRAC acts like a resistor and converts signal to read out on speedo. I just need ot know which wire to splice into to make it work.

71403

The VSS output from the PCM goes to the speedometer input on the dash. You could pick it up at the DRAC but the DRAC does not need to remain connected.

gofastwclass

iTrader: (2)

Exactly. The DRAC was crossover technology that isn't necessary with the newer PCM's. One of many things you can toss out the window with your swap.

gmfanatic92

iTrader: (-2)

got it working thanks 71403 and gofastwclass


no more DRAC needed

Anthony213

@gmfanatic92 how did you get it to work ? I am in the exact same spot you were in what wire did you end up splicing ?

ls1nova71

iTrader: (4)

gmfanatic92 hasn't been on here in over 8 years. But to answer your question, you just run the speedo out from the PCM directly to the speedometer. I don't know what engine you have, but on a GenIII it's usually C2 pin 50. You don't need the DRAC.

Anthony213

I have a 1994 c1500 and i swapped in a 4.8 ls would
it still be the same pin ?

ls1nova71

iTrader: (4)

What year is your engine/PCM? Thats what makes the difference.

Anthony213

I actually got it to work thank you . Just had to tie in my standalone speedometer wire to the existing one from my drac