47RE Vehicle Speed Sensor and wire harness

[charlessmith]

I've had a couple occurences of heavy throttle very fast 3-2-3 3-2-3 shifting in my '96. Talking to Dave Goerend, he suggests it can be the vehicle speed sensor or it's wiring harness.

Most recent occurance was pulling 10 mile 6% grades in the Rockies, 5000# load in the truck, running (about) 2300 RPM in 3rd. When I gave it a little bit more throttle to pick up 2 or 3 MPH it would go through very quick 3-2-3 shifts, the 3-2-3 shift occuring in about a half second. I'd see the tach bounce to around 3000 RPM and back. This would keep happening until I got my foot off the throttle, just my reaction time to lift my foot would produce 3 or 4 of the down-up shifts.

Being in OD or out of OD made no difference. I tried shifting into OD but the problem was still the same. I flipped a switch to use my 1k-5k pot instead of the TPS and this made no difference.

After pulling off in a level spot to check the transmission fluid level (it was fine) when I got back on the road the problem would not happen again.

I've had the same thing happen a couple times previously, but since it would not repeat after stopping, I couldn't figure out what was happening.

Dave Goerend said the PN on the speed sensor is 4800879 and the PN on it's wiring harness is 5013950A.

Is it much of a big deal to replace the sensor and harness? Am I right to assume the harness just goes from the speed sensor to the ECU? (and not half way around the truck).

Does anybody else have an idea what may be happening?