Speed Signal Interface Converts VSS to ECM Signal

The SN74Z has the following features when used as a Speedometer interface.

Input Source Options

• Three wire pulse signal generator input source
• Built-in Vehicle Speed Sensor (VSS) input source
• Most Tremec transmissions
• Later model 700R4
• Typically a sine wave signal
• Two wire pulse signal generator input source
• Classic Instruments SN96 or SN95
• Typically a sine wave signal
• One wire ECM signals input source
• Typically a 5 volt square wave output
• The output can be selectable between either 8000 pulse per mile or 16000 pulse per mile
• Outputs a 12V square wave, 50% duty cycle
• 8000 pulse per mile cruise control output
• Three different calibration options
• Drive 30 MPH and press the calibration button
• Real-Time: press and the hold the calibration button to match the speedometer reading to the actual vehicle speed
• Drive a measured mile to calibrate the speedometer
• Input signal can range from 2000-200,000 pulses per mile
• State of the art signal averaging software that ensures smooth pointer operation, even in fluctuating signal conditions.
• Noise-reducing, filtered power output for powered speedometer signal generators
• The SN74Z has the following features when used as a Tachometer interface
• Input Source Options
• High Voltage Coil signal input source
  .5-6 pulses per revolution (1-12 cylinder engine)
• Typically the negative side of an ignition coil
• 5-12 Volt Square Wave signal input source
• .5-6 pulses per revolution (1-12 cylinder engine)
• 20%-50% duty cycle
• Typically from an electronic ignition box or computer
• Inductive Gear tooth sensor input source
• Typically used in diesel applications where there is not an ignition system
• The sensor can be mounted to the engine near the flywheel to sense the gear teeth as they rotate by
• Can be used with 32-510 tooth flywheels, 32-510 pulses per revolution

Signal Output

• 12V square wave, 50% duty cycle
• 2, 3 or 4 pulses per revolution (4, 6 or 8 cylinder)
• 3 preset flywheel tooth settings
• 148 tooth Chevy Duramax
• 152 tooth 5.9L Cummins
• 155 toothndash 7.3L Ford Powerstroke