Mercury MerCruiser MCM 454 Mag MPI Service Manual page 693

GENERAL SYSTEM DIAGNOSTICS
Discrete Input Circuit Check - Non-Scan 7.4L MPI Only (3 of 5)
TESTING GEAR LUBE MONITOR SWITCH
STEP
1
2
3
4
TESTING TRANSMISSION TEMPERATURE SWITCH
STEP
1
2
3
4
Index
Page 5E-100
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ACTION
1. Disconnect TAN/WHT wire from gear
lube monitor.
2. Empty gear lube from monitor.
3. Check for continuity between TAN/WHT
wire and ground (–).
Is there continuity?
1. Refill gear lube monitor.
2. Check for continuity between TAN/WHT
wire and ground (–).
Is there continuity?
Replace gear lube monitor. Verify repair.
Gear lube monitor switch is working properly.
ACTION
1. Disconnect both wires from transmission
temperature switch.
2. Ensure switch is at a cool temperature
(less than normal operating temperature).
3. Check for continuity between both termi-
nals.
Is there continuity?
1. Heat the switch to a temperature high
enough to activate it. (Refer to Section 4D of
this manual for procedure).
2. Check for continuity between both termi-
nals.
Is there continuity?
Replace transmission temperature switch.
Verify repair.
Transmission temperature switch is working
properly.
SERVICE MANUAL NUMBER 23
VALUE YES NO
PROCEED TO
0 Ohms Step 2 Step 3
0 Ohms Step 3 Step 4
–
–
VALUE YES NO
PROCEED TO
0 Ohms Step 3 Step 2
0 Ohms Step 4 Step 3
–
–
90-861326--1 MARCH 1999
–
–
–
–