2003 ST 4 Stroke 9.9/15HP Johnson outboards Service Manual, Page 77Get this manual
IGNITION AND ELECTRICAL STARTER MOTOR Check: Relay operation (Continuity between the relay terminals)
Digital tester Tester selector:
1Disconnect: Relay wires (YG and B) Cable and wire on terminal CD, (2) Tester probe connection Probe Terminal Other probe
Terminal (2)
2Use 12V Battery3Connect: Yellow Green wireBattery Black wireBattery 8
When 12V appliedContinuity When 12V not applied -Infinity
12 Battery
If out of specificationReplace