Abstract: A multiple function testing device has four circuits for measuring various functions of an internal combustion engine. The circuits are a cam dwell angle measuring circuit, a tachometer circuit, a voltmeter circuit and a timing light. The device is designed such that the cam dwell measuring circuit, tachometer circuit and voltmeter circuit use a common meter. Any one of these three circuits may be selectively operated simultaneously with operation of the timing light for simultaneous measurement of timing and one of dwell angle, R.P.M. or voltage.