Diagnostic Aids

Code 24 will set when no vehicle speed is detected at vehicle start off. Code 72 will set when VSS signal is present and is lost. Check all connections, especially those at transmission pass-through connector. If code is intermittent, see INTERMITTENTS in TESTS W/O CODES - GASOLINE article. While Code 24 is set, scan tester will display an RPM derived from input speed. If input speed sensor is not operational at start-up, this can cause VSS to read zero.

Fig 1: Code 24 Schematic ("C" & "K" Series) VSS Transmission Output Signal

Fig 2: Code 24 Schematic ("G" & "P" Series) VSS Transmission Output Signal

Fig 3: Code 24 Schematic ("L" & "M" Series) VSS Transmission Output Signal

Fig 4: Code 24 Schematic ("S" & "T" Series) VSS Transmission Output Signal

Fig 5: Code 24 Flow Chart (All Models) VSS Transmission Output Signal