Proper Tools and Testing Procedures

DIGITAL VOLT/OHM METER
Use a digital volt/ohm meter (DVOM) with a minimum 10 mega-ohms internal impedance when testing an PCM or related components, unless use of an analog meter is specified by a testing procedure. Analog meters have low internal impedance and cause circuit "loading" in low voltage circuits, resulting in inaccurate measurements and possible damage to components. Use of a DVOM is necessary to obtain accurate measurements and to avoid damage to low voltage PCM circuits and components.


TESTING PROCEDURES
Always follow recommended testing procedures. Never ground or apply voltage to a circuit unless specified by a testing procedure. PCM's provide a regulated constant low voltage source to some circuits, which may require a minimum resistance (impedance) to operate. Directly grounding or applying battery power to these circuits could damage the PCM and cause a system failure.