Manifold Absolute Pressure (Map) Sensor Ohms Test; Idle Speed Control; Rpm-Limit Circuit - Mercury 150 EFI Service Manual

IGNITION

Manifold Absolute Pressure (MAP) Sensor Ohms Test

RED METER RED METER
LEAD

Idle Speed Control

The ECM varies the timing and the fuel flow based on the throttle opening to maintain an
idle speed of 650 rpm

RPM-Limit Circuit

The rpm limit circuitry is contained within the ECM. When the rpm limit point is reached
(this point will vary between engine models), a warning horn will sound. If the rpm contin-
ues to increase, ignition spark will be cut to cylinders #1, #3 and #5. If the rpm still contin-
ues to rise, fuel and ignition spark will be cut to all cylinders.
Page 2A-26
BLACK METER LEAD
BLK/ORG
PIN A
BLK/ORG
PIN A
YEL 95000 – 105000
PIN B
PPL/YEL 3900 – 4100
PIN C
50 rpm.
YEL
PIN B
X 95000 – 105000
ohm
X
ohm
95000 – 105000
ohm ohm
58904
PPL/YEL
PIN C
3900 – 4100
ohm
95000 – 105000
ohm
X
90-883728 JULY 2001