Vehicle Speed Sensor Circuit Schematic - LM2917N VSS to 5V ECU Input

This document is a hand-annotated electronic schematic titled "Vehicle Speed Sensor Circuit." It shows a frequency-to-voltage/speed signal conditioning circuit built around an LM 2917N IC powered from +12V. Supporting components include a 10K resistor from the 12V rail to pin 11, a 470R resistor to pin 9, an IN4148 diode and 100K resistor on the sensor input side, C1 and VR1 (an adjustable trimmer) on pins 2 and 4, a 2.2uF tantalum capacitor, a 6.2V Zener diode on the output, and a 10K resistor to 0 Volts inside a dashed box producing a "Speed Signal to De-Coupler." A later annotation (bold black wire) shows the output tapped through an in-line 10K resistor with a red-drawn pull-up resistor to 5V, feeding an "MS INPUT" (likely a MegaSquirt or similar ECU input). Notes state the circuit is for the DRIVEN circuit only, recommend putting a switch on the sensor input to turn traction on and off, and caution not to turn the undriven sensor off unless the driven one is off too, or traction control would activate. The document contains no year, make, or model information itself.