Code 23: Intake Air Temperature (IAT) Sensor Circuit (Non-Scan)
(1 Of 2)
INTAKE AIR
TEMPERATURE
SENSOR
B
A
IAT
CIRCUIT DESCRIPTION:
DIAGNOSTIC AIDS:
The Intake Air Temperature (IAT) sensor uses a
thermistor to control the signal voltage to the Elec-
tronic Control Module (ECM). The ECM applies a
voltage (about 5 volts) on CKT 472 to the sensor.
When the air is cold, the sensor (thermistor) resis-
tance is high; therefore, the ECM will see a high sig-
nal voltage. If the air is warm, the sensor resistance
is low; therefore, the ECM will see a low voltage.
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.
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. If
Code 21 is also set, check CKT 813 for faulty wiring
or connections. Check terminals at sensor for good
contact.
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the
diagnostic chart.
1.
A Code 23 will set due to an open sensor, wire,
or connection. This step will determine if the wir-
ing and ECM are OK.
2.
If the resistance is greater than 25,000 ohms, re-
place the sensor.
Index
5C-90 - 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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