Help with yellow box vs. VSS?
 

So I'm quite unsure of myself but. I got a check engine light back in april. When I first checked it with the OBD II scanner the code that came out was P0500. My initial thought was to replace the VSS ( vehicle speed sensor) thinking maybe it went bad. But i continued to do further research. I found a post by Billman a few years back that if you have a yellow box, this could be a disrupting factor as to why this is happening because it is not able to translate your speed accurately. I'm running 4.77 gears, so should i just remove the yellow box entirely , but if i do my speedometer will be off like maybe 10mph. So if im going 50mph im really going like 60mph or something like that. I'm trying to get a better understanding on how the yellow box and VSS work together, so I can determine whether to remove the box or just replace the VSS.

- on a side note; the other day my vtec stop engaging. When i got to like 7k the car felt like it hit a brick wall. And i changed the oil 400 mi ago. Its still kinda brand new. So I'm thinking what ever is going on electrically is putting the cars computer in a safe mode that wont allow it to go all the way.

Please any advice or opinions that could help me on why this may be happening, id greatly appreciate it, Thank you!

Some ECUs use an alternate (and lower) rev limit in case the VSS stops working. For example, a 1996 to 1999 BMW M3 ECU.

This should answer the how it works.
http://yellr.com/speed_works2.gif

http://yellr.com/yb_works4.gif

In the case of the S2000, the VSS is split in the wire harness and feeds the Gauge cluster and ECU. Depending on where you installed the YB and how it is connected will dictate where the root cause is. If it was installed using the Plug-n-Play, it is powered by the same power source as the VSS and both the ECU and Gauge Cluster see the same speed signal rate. If it is installed under the dash, it is most likely connected to the gauge cluster only vss signal.

So besides the P0500 what other issues are you seeing?

I have a 3.9 ratio in my rear assembly. I've installed a Yellow Box in the plug-n-play configuration and I'm now getting a P0500 code. Are you, Stratocaster , saying that I ought to remove it from plug-n-play and install it with output to the gauge cluster only?

That's a pain in the ass but I'll do it.