MIL-DTL-62738A

Abstract

This specification covers an Ignition Interrupt Driver Printed Wiring Assembly referred to herein as the PWA. This is one of six printed wiring assemblies which comprise the Simplified Test Equipment/Internal Combustion Engine-Reprogrammable (STE/ICE-R) Vehicle Test Meter (VTM) (see Drawing 12259265). <b><u>Intended Use:</u></b> The PWA consists of special circuitry to interface to an automotive spark ignition system. This module has Points Voltage (POINTS V), and Ignition Kill (IGN KILL) as its inputs, and Ignition Signal (ING SIG) and POINTS V as its outputs. This module can either interrupt or continuously inhibit spark ignition according to the control signal IGN KILL. The Points Signal is transformed by circuitry utilizing an optocoupler (UI) into logic levels suitable for detection by the VTM through the signal IGN SIG. The interrupt or inhibit signal, IGN KILL, is transformed from VTM logic levels into signals driving a transistor circuit (Q1 and Q2). The transistor circuit pulls the POINTS V down to a level such that the spark plugs in the engine will not fire. The PWA is military unique because it is designed specifically to be a component of the Simplified Test Equipment/Internal Combustion Engine - Reprogrammable (STE/ICE-R) Vehicle Test Meter (VTM) and to withstand environmental conditions which exceed commercial requirements. <br>