TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
Code 25 (3 of 3): Intake Air Temperature (IAT) Sensor Circuit (Non-Scan) High
Temperature Indicated
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 IAT sensor harness terminals.
Ignition “ON,” engine “OFF.”
Connect DVOM across the sensor harness
terminals.
Is voltage above the specified value?
4 Volts
–
Step 3
Step 4
–
Locate and repair intermittent faulty connec-
tions. If OK, replace faulty IAT sensor.
3
4
5
Locate and repair short to ground in CKT 472.
If a problem is found, repair as necessary. Was
a problem found?
Verify
Repair
–
–
Step 5
–
Repair faulty ECM connections or replace
faulty ECM. Is action complete?
INTAKE AIR TEMPERATURE SENSOR CHART
IAT Sensor
Temperature - to - Resistance Values (Approximate)
°
F
°C
OHMS
210
160
100
70
40
20
100
70
38
20
4
-7
-18
-40
185
450
1,800
3,400
7,500
13,500
25,000
100,700
0
-40
Page 5G-18
90-861326--1 MARCH 1999
| 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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