Diagnostics-Without Scan Tool
Code 14: Engine Coolant Temperature (ECT) Sensor Circuit (Non-Scan)
(1
of 2)
ENGINE
ENGINE
CIRCUIT DESCRIPTION:
3. This step will isolate the problem to CKT 410 (5
volt reference) or to the sensor ground.
The Engine Coolant Temperature (ECT) sensor uses
a thermistor to control the signal voltage to the ECM.
TheECMappliesavoltageonCKT410tothesensor.
When the engine coolant is cold, the sensor (thermis-
tor) resistance is high; therefore, the ECM will see
high signal voltage.
4. This step identifies if CKT 410 is open or shorted
to ground.
DIAGNOSTIC AIDS:
An intermittent problem may be caused by a poor or
corroded connection, rubbed through wire connec-
tion, a wire that is broken inside the insulation, or a
corroded wire.
As the engine coolant warms, the sensor resistance
becomes less, and the voltage drops.
TEST DESCRIPTION:
Any circuitry that is suspected as causing the inter-
mittent complaint should be thoroughly checked for
backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, poor
terminal-to-wiring connections, corroded terminals
and/or wiring, or physical damage to the wiring har-
ness. After repairs, clear codes following “Clearing
Codes” in “ECM Self-Diagnostics.” Failure to do so
may result in codes not properly being cleared.
Check harness routing for a potential short to ground
in CKT 410. See “Intermittents” in “Troubleshooting.”
Number(s) below refer to circled number(s) on the
diagnostic chart.
1.
This step checks if there is a problem with the
ECM and wiring or if the problem is the coolant
sensor.
2.
Check the harness terminals thoroughly for loose
connection. If the resistance or the coolant sen-
sor is monitored, the resistance should steadily
decrease as the engine coolant warms up. The
resistance reading would stabilize when the ther-
mostat opens.
IMPORTANT: If replacing the ECT, tighten hand
tight plus 2-1/2 turns maximum.
Index
5C-86 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
90-823224--2 796
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
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