Mercury MerCruiser MCM 454 Mag MPI Service Manual page 719

TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 14 (2 of 2): Engine Coolant Temperature (ECT) Sensor Circuit (Scan)
Number(s) below refer to step number(s) on the diagnostic table.
Step 2. Code 14 will set if:
Signal voltage indicates a coolant temperature above 266 F (130 C).
Signal voltage indicates a coolant temperature below -22 F (-30 C).
Step 6. This test will determine if CKT 410 is shorted to ground, which will cause the condi-
tion for Code 14.
STEP
1
2 2
3
4
5
6 6
7 7
8
9
10
11
Index
Page 5F-22
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ACTION
Was the "On-Board Diagnostic" (OBD) System
Check Performed?
1. Ignition ON.
Does scan tool display a coolant tempera- p y
ture value greater than 266 F (130 C) or
less than -22 F (-30 C)?
Does scan tool display a coolant tempera-
ture value greater than 266 F (130 C)?
Does scan tool display a coolant tempera-
ture value less than -22 F (-30 C)?
Code 14 is intermittent. If no additional codes
were stored, refer to "Diagnostic Aids."
1. Ignition OFF.
2. Disconnect engine coolant temperature
(ECT) sensor.
3. Ignition ON.
4. Scan tool should display coolant tempera-
ture below -22 F (-30 C)
ture below -22 F (-30 C).
Does it?
1. Ignition OFF.
2. Disconnect coolant temperature sensor.
3. Jumper terminals "A" and "B" together.
4. Ignition ON.
5. Scan tool should display coolant tempera-
ture above 266 F (130 C). ture above 266 F (130 C)
Does it?
Check for CKT 410 shorted to ground or faulty
ECM.
Replace engine coolant temperature sensor.
Check CKT 410 open, sensor ground open, or
faulty ECM.
Replace engine coolant temperature sensor.
SERVICE MANUAL NUMBER 23
VALUE YES
PROCEED TO
– Step 2
p
– – Step 3 Ste 3
– Step 6
– Step 7
– –
– – Ste 9 Step 9
– Ste 11
– Step 11
– –
– –
– –
– –
90-861326--1 MARCH 1999
NO
Go to
OBD
System
Check
Ste 5 Step 5
–
–
–
Ste 8 Step 8
Ste 10
Step 10
–
–
–
–