boostd4

I have a 93 RX7 with a 99 LS1 swap.

I'm in the process of cleaning up the previous owners spaghetti rats nest at the PCM, and simultaneously wiring up a Dakota Digital speedo converter and have a few questions, mostly curiosity.

I see that pins C2-20 and C2-21 are VSS Low and VSS high. Are these the VSS input from the sensor? What is the function of having a high and low input?

I also see that pin C2-50 is Vehicle Speed Output Circuit. What function does this serve on a Camaro/Firebird/etc?

I've been doing a bunch of research and it seems most swap-cars/hybrids are using the VSS High to feed a speedo or speedo converter. The speedo has never worked in my car and the (RX7 specific) instructions say to tap the VSS High wire.

Odly, the previous owner has tapped the Vehicle Speed Output Circuit wire at the LS1 PCM (C2-50) instead.

Does this wire coming off the PCM need to see some sort of voltage/ground? It seems it's been connected in error, will cutting it and taping it off (not connected to anything after the PCM) cause any problems? I plan to use the VSS high (C2-21) instead.

Thanks!

shoemike

iTrader: (25)

C2-20 and C2-21 go to the PCM from the VSS (DIFF/TRANS).
C2-50 goes to the IPC (speedometer) BCM, CC, Radio from the PCM.
Low signal=.1 volt ground

poconojoe

iTrader: (43)

If you would read DD instructions, you would find they recomend using the PCM output not the raw VSS signal to drive their convertor. you need to set the the switches a little differant to do it. Most of the RX7 swap guys set them for Off, Off, On, On to use the VSS signal directly, to use the PCM input IIRC it should be On, On, On, Off. If you would read the instructions, you would also find that if you tap the VSS output directly, you shouls use both leds and twist the wires together, I guess Danzan can't read, and doesn't like being told he's wrong. The VSS output on the LS PCM's is normally 4000 pulses per mile. most of the RX (if not All) speedometer require 8002 pulses per mile to read correctly. so if you use the DD on the VSS output you need to set it for approx. 1:2 output. You could also just set the PCM to output 8000 PPM (you can't set it for 8002, since the number has to be divisable by 4) and try to directly feed the RX7 speedometer, but I had no luck doing this, since for some reason the RX7 speedomter didn't like the LS PCMs's output pulse. You might have better luck then me with this, since I didn't have a lot of time to play with thie and the guy had already bought the DD box.
Here are the DD instructions, if you don't have them
http://www.dakotadigital.com/pdf/sgi-5c.pdf

There are no (RX7 specific) in the above documnet, the ones that are posted everywhere are just somebody's opinion of how it should be done, even though, they're not following DD recomended method and what ever you do don't question them (on the RX forums)about why they recomend doing it wrong, they'll have your posts deleted