Mechanical Speedometer and vss?

[c0olburn3r]

Hey guys, I have a 1987 SILVERADO, 350 TBI, 700 R4 tranny with a mechanical cable for speed.
I purchase autometer mechanical gauge for the odometer but I noticed I had to take a 3 wire connector from the original odometer that was held in place with one small bolt....looks like a magnetic counter of some sort. did a little digging and it looks like a vss sensor?. anyhow my problem is that the tranny will not go to overdrive since I installed the gauge and left that connector out. does anyone have  an idea if there is a adapter of some sort cause I like my overdrive and don't want to mess up the tranny.
Thank you

[LTZ C20]

What you have done by unplugging the VSS sensor is removed the ECM'S source of vehicle speed, so know it won't lock the torque convter because it doesn't know how fast your going, it can also cause a few running issues, such as you let of the gas to slow down, the ECM sees a drop in throttle position but no drop in speed as you slow down. This manages the amount of fuel supply and timing adjustments. It can also cause your Service Engine Soon or Check Engine light to come on, setting a code for loss of speed sensor signal. The VSS is a magnetic pickup counter, there is a reluctor wheel on the output shaft of the transmission, changes in how fast the shaft spins determines vehicle speed.

Why did you hook up an auto meter gauge? Was the factory odometer not working?

[c0olburn3r]

I changed all the gauges , wanted something a little more modern and seen other people on here that changed them as well, my question is there an adapter out there or do I need to order a different gauge

[bd]

Downloadable speed sensor reference directly from the Jaguars That Run website:  "V8 TBI/TPI Speed Sensors."  The VSS generator you're seeking is marketed under P/N 2PRS and attaches directly to the transmission speedo gear adapter.   Depending on your exhaust configuration, you may need to use a speedometer cable extension that provides flexibility in the installation.  P/N 2PRS-EXT includes a 10" extension speedometer cable that inserts between the VSS generator and speedo gear adapter.  There maybe other sources that provide similar offerings.  Dakota Digital (which is sold by our store) markets VSS generators for their instrument clusters that I believe are 8,000 PPM, four times OE TBI.  Check with Captkaos at webmaster@73-87chevytrucks.com to be sure.

[LTZ C20]

There ya go, BD nailed it pretty good. Howell Engine Developments also sells 1 or 2 adapters. I'm running 1 of their's. I attaches directly to the speed gear housing on the transmission, let's me use my orginal mechanical speedo but produces signal for the ECM'S various functions. I'm running a TBI 350 with 4L60 trans.

[c0olburn3r]

Thank you so much for the information, I ordered the P/N 2PRS , not bad for 85 dollars. I will let you guys know how it worked out.
Again thank you.