SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 23 (2 of 2): Intake Air Temperature (IAT) Sensor Circuit (Scan)
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
Step2.ACode23willset,duetoanopensensor,wireorconnection.Thistestwilldetermine
if the wiring and ECM are OK. If the scan tool indicates a temperature of over 266°F (130°C),
the harness to the sensor should be checked before replacing the sensor.
Step 4.This will determine if the IAT sensor signal (CKT 472) or the IAT sensor ground (CKT
813)
is open.
Step 5. This step will determine if the fault is in the IAT sensor or the circuit.
STEP
ACTION
VALUE
YES
NO
PROCEED TO
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
1
–
Step 2
Check
Ignition ON.
Does scan tool indicate display an intake
air temperature of less than -22° F (-30° C)?
Does scan tool indicate display an intake
air temperature greater than 266° F (130°
C)?
–
–
Step 3 Step 11
Step 5 Step 11
2
1.
2.
3.
4.
Ignition OFF.
Disconnect IAT sensor.
Jumper harness terminals together.
Ignition ON.
3
4
Does scan tool should display temperature
greater than 266° F (130° C)?
–
–
Step 8
Step 6
Step 4
Step 7
1. Ignition OFF.
2.
3.
Jumper CKT 472 to engine ground.
Ignition ON.
Does scan tool should display temperature
greater than 266° F (130° C)?
5
1. Ignition OFF.
2.
4.
Disconnect IAT sensor.
Ignition ON.
Does scan tool should display temperature
less than -22° F (-30° C)?
–
–
–
Step 10 Step 9
Open sensor ground circuit, faulty connection
at ECM, or faulty ECM.
6
7
–
–
–
–
Open CKT 472, faulty connection at ECM, or
faulty ECM.
8
9
Faulty connection or IAT sensor.
CKT 472 shorted to ground or faulty ECM.
Faulty IAT sensor.
–
–
–
–
–
–
–
–
–
10
Code 23 is intermittent, refer to “Diagnostic
Aids” on facing page.
11
–
–
–
Index
90-861326--1
MARCH 1999
Page 5F-27
| 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 |
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