Ok so I've got my 3800sc up and running. Its a blast to drive but my speedometer isn't working.
It turns on and moves to 0mph when I turn the car on, and before the swap it worked fine.
I built a converter by following this diagram (I also used the GMtuners pinouts and my wiring harness is working fine)

The PCm is outputting the speed correctly to the OBDII port, and I'm using a real time scan gauge and its reading the speed correctly.
If anyone can give me a list of what I need to buy I'd really appreciate it, or a picture of one of these converters built.
I'm questioning if I bought the wrong components or oriented them wrong and thats what my issue is.
Thank you
Jessica

http://www.reddevilriver.com/ Sells one prebuilt under related products for 20.00.

Could be a couple things.
1) when soldering the components together, don't apply too much heat or you can damage the parts.
2) make sure that the components aren't touching each other, they could ground out.
3) the diode has a line on it and has to be the right direction, hence the arrow in the diagram
4) I think on the yellow wire to the speedo I spliced into it, not remove one end.

Good luck fixing it and awesome job on getting a swap done!

EDIT:

Capacitor
https://www.radioshack.com/...zBtdICFQ6raQodFckN_g

22k Resistor
https://www.radioshack.com/...bCtdICFQe5wAodzWQKEw
1k resistor
https://www.radioshack.com/...n-film-resistor-pk-5

Diode
https://www.radioshack.com/...4001-micro-1a-diodes

I will add a picture tonight

I snagged pics off the web to show you what it should look like. Forgot mine is all shrink wrapped.



------------------
-Brian

My 87 GT Poly Suspension Upgrade (all pics) thread
Removing the roof panel
My HUD install thread
Modified stock air canister and base to 3.5 inch for 3800na

[This message has been edited by MulletproofMonk (edited 03-05-2017).]

Thank you so much! And I will wait to see the picture, I'm sure that will help. I'm using the car as my daily driver right now but that should only be for another week or so.
Then I can get back into the wiring and try to fix this, and see if the cruise works.
Jessica

Sorry for the delay Jessica. Mine is all shrink wrapped, but this visual should show you exactly what it should look like when you build it.

Before you solder it to the C203 and hook it to the PCM, make sure to slip some shrink wrap over the three connections to make sure they don't touch. Also note that the line on the diode should be towards the PCM (the same way the >| is in Ryan's diagram).

------------------
-Brian

My 87 GT Poly Suspension Upgrade (all pics) thread
Removing the roof panel
My HUD install thread
Modified stock air canister and base to 3.5 inch for 3800na

[This message has been edited by MulletproofMonk (edited 03-05-2017).]