Mercury MerCruiser MIE 8.2L MPI User Manual

TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
90-861326--1 MARCH 1999 Page 5G-5
Code 14 (2 of 3): Engine Coolant Temperature (ECT) Sensor Circuit
(Non-Scan) Low Temperature Indicated
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
Step 2. This step checks if there is a problem with the ECM and wiring or if the problem
is the ECT sensor.
Step 3. This step will isolate the problem to CKT 410 (5 volt reference) or to CKT 814
(sensor ground).
Step 4. Check the harness terminals thoroughly for loose connections. If the resistance
of the ECT sensor is monitored, the resistance should steadily decrease as the engine
coolant warms up. The resistance reading should stabilize when the thermostat opens.
STEP
ACTION VALUE YES NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
– Step 2
Go to
OBD
System
Check
2 1. Ignition “OFF.”
2. Disconnect ECT sensor harness terminals.
3. Ignition “ON,” engine “OFF.”
4. Connect DVOM across the coolant sensor
harness terminals.
Is voltage above the specified value? 4 Volts Step 4 Step 3
3
1. Connect positive (+) DVOM lead to harness
terminal “B” CKT 410 (5 volt reference).
2. Connect negative (–) DVOM lead to a
known good ground.
Is voltage above the specified value? 4 Volts Step 6 Step 5
4
Locate and repair intermittent faulty connec-
tions. If OK, replace faulty ECT sensor.
Is
action complete?
– –
5
Locate and repair open CKT 410. If a problem
is found repair as necessary.
Was a problem
found?
–
Verify
Re
p
air
Ste
p
7
6
Locate and repair open ground CKT 814. If a
problem is found, repair as necessary.
Was a
problem found?
–
Re air
Ste
7
7
Repair faulty ECM connections or replace
faulty ECM.
Is action complete?
– –
Downloaded from https://needmanual.com/!
Index

Mercury MerCruiser MIE 8.2L MPI Specifications

General

Brand	Mercury
Model	MerCruiser MIE 8.2L MPI
Category	Engine
Language	English