Mercury 90 - Page 148

Dual Outboards
Connect a common ground cable (wire size same as engine battery cables)
between negative (–) terminals on starting batteries.
a - Red sleeve ‑ positive (+)
b - Black sleeve ‑ negative (–)
c - Ground cable
d - Cranking battery
(-)
(-)
a
a
b
b
c
d
d
15497
OUTBOARD INSTALLATION
138 eng