SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 7.4L MPI
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
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
Check
1
2
–
Step 2
1. Ignition “OFF.”
2.
3.
4.
Disconnect ECT sensor harness terminals.
Ignition “ON,” engine “OFF.”
Connect DVOM across the coolant sensor
harness terminals.
Is voltage above the specified value?
4 Volts
Step 4
Step 6
Step 3
1.
terminal “B” CKT 410 (5 volt reference).
Connect positive (+) DVOM lead to harness
3
2.
Connect negative (–) DVOM lead to a
known good ground.
Is voltage above the specified value?
4 Volts
–
Step 5
–
Locate and repair intermittent faulty connec-
tions. If OK, replace faulty ECT sensor. Is
action complete?
4
5
Locate and repair open CKT 410. If a problem
is found repair as necessary. Was a problem
found?
–
Verify
Repair
Step 7
–
Locate and repair open ground CKT 814. If a
problem is found, repair as necessary. Was a
problem found?
6
7
–
–
Repair faulty ECM connections or replace
faulty ECM. Is action complete?
90-861326--1
MARCH 1999
Page 5G-5
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(1 votes, average: 5 out of 5)
Marine readers have rated Mercury MerCruiser GM V8 GM V8 454 CID 7.4L and 502 cid 8.2L Marine Engines Service Manual Number 23 5.0 out of 5.0 based on 1 product reviews. Just need the manual. Wrote review. Can't technically review what I haven't seen yet...