V-MAC Co-Pilot Operator’s Manual 59 ELECTRICAL ACCESSORY CONNECTION POINTS This MACK chassis is electrically ready for convenient installation of electrical accessories. Use the designated battery post (+12 V), ground post, CB jack, buffered RPM outputs, buffered mi/h outputs, and the SAE/ATA J-1708 post located on the electrical equipment panel for the installation of any electrical accessories. Each connection point is described below.
Battery Post (BATT) This is a +12 volt, unswitched battery power connection. It can be used to power external devices that require power at all times, even when the ignition key is turned OFF. This source is protected by a 15-amp circuit breaker.
Ignition Post (IGN) This is a +12 volt, switched battery power connection. It can be used to power external devices that require power only when the ignition key is ON. This source is protected by a 15-amp circuit breaker.
Ground Post (GND) This is a ground connection. It can be used as a power return (−) connection for external devices.
RPM Output This is a 50% duty cycle, 5-volt transistor-transistor logic (TTL) compatible, square-wave signal that is calibrated to provide a standard pulse rate of 12 pulses per engine revolution. Note: Transistor-transistor logic compatible of this output may be affected by other devices connected to this output. Maximum rated current of the TTL output is 10 mA. Total current draw of all devices connected to this output must not exceed 10 mA at 4 volts.
