1978 Ski-Doo Shop Manual, Page 284Get this manual
SECTION 05 SUB-SECTION 03, (MERC-O-TRONIC TEST)
TEST NO.1 IGNITION COIL POWER TEST
For test no1 and 2, the battery normally installed in the analyser has insufficient voltage to produce exact readings requiredTherefore, disconnect the analyser battery cables at the battery posts and connect each cable to appropriate post of 12 volt batteryTest condition of the connected 12 volt battery as detailed in analyser test1Connect the black test lead the ignition coil
to terminal no15 of
2Connect the red test lead to terminal no1 of ignition coil3Connect the single red test lead terminal