Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 49Get this manual
IGNITION SYSTEM
Trigger Coil ACAUTION
DO NOT rotate flywheel during test or damage to meter may result1Use an ohmmeter to periorm the following test149223Q
2If meter readings are other than specifiedreplace trigger coilRefer to "Ignition Compo nents Removal and Installation," following
Ignition Coil