P0500

P0500 indicates the PCM is receiving no vehicle speed signal during conditions where one is expected, typically with the engine running and the transmission in a driven gear. The code disables cruise control, may freeze the speedometer at zero, and on many vehicles causes harsh shifts because the TCM uses VSS for shift scheduling. Start with the cheapest checks: scan live data and compare VSS to the speedometer needle during a slow roll. A healthy VSS produces a clean AC square wave that scales linearly with road speed, typically 5 to 8 Hz per mph for a Hall-effect tone-ring sensor, so 30 mph should show roughly 150 to 240 Hz on a scope. If the live VSS reads zero while the speedometer works, the fault is downstream of the cluster on the CAN/class-2 bus; if both read zero, suspect the sensor, its tone ring, or the wiring. Inspect the connector for corrosion and back-probe the signal wire for the AC waveform before condemning anything. The expensive misdiagnosis is replacing a transmission or ABS module when a $40 sensor or a chafed harness ground is the actual cause.

Vehicle-specific patterns: 1999 to 2006 GM full-size trucks and SUVs with 4WD lose speedometer and set P0500/P0501 from a failing transfer case output speed sensor on the NP246/NP263 case, GM TSB 02-04-21-004 covers the symptom. 2005 to 2010 Honda Odyssey and Pilot set P0500 from the VSS mounted in the transmission case, internal solder failure is common past 120k miles. 2002 to 2008 Dodge Ram with 5.7 Hemi sets P0500 from a corroded output speed sensor connector at the rear of the 545RFE. 2003 to 2007 Ford F-150 with 4R70W/4R75W sets P0500 from a failed OSS internal to the transmission, requiring pan-drop access. Estimated repair: $80 to $450.