1997 Ski-Doo Factory Shop Manual Volume Two, Page 194Get this manual
Section 05 ELECTRICAL Sub-Section 02 (WIRING DIAGRAMS)
ACCESSORIES INSTALLATION
On all electric start models: The direct current (DC) utilizes the snowmobile frame as ground "wire" while all alternating current (AC) consumers (lights, heated grips, fuel gauge, etc utilize separate ground wireNever interconnect AC and DC grounds as an AC voltage drop will resultWhen installing accessories on any snowmobile, connect their wires directly to the YELLOW and YELLOW BLACK lighting coil wiresEven if manual start models have an AC ground to the chassis (on voltage regulator), all accessories utilize ground wire isolated from chassisWhen an electric starter kit is installed, the voltage regulator and its ground wire are replaced by voltage rectifierregulator unit permitting completely isolated AC circuit1