SERVICE MANUAL NUMBER 24
DIAGNOSTICS
Code 25 (2 of 2): Engine Coolant Temperature (IAT) Sensor Circuit
Step
Action
Yes
No
PROCEED TO
Was the “On-Board Diagnostic” (OBD) System Check
Performed?
1.
2.
Step 2.
OBD
Are you using a Scan Tool?
Step 3. Step 7.
Ignition ON.
3.
Does the scan tool display a temperature greater
than 266°F (130°C)?
Step 4. Step 5.
a. Ignition OFF.
b. Disconnect IAT harness connector.
c. Ignition ON, engine OFF.
4.
Does scan tool display a temperature below -22°F
Step 8. Step 6.
(-30
°C)?
Trouble code 25 is intermittent. Locate and repair inter-
mittent faulty connections. Refer to “Diagnostic Aids.”
5.
6.
–
Verify
Repair
Locate and repair short to ground in CKT 472. If a prob-
lem is found, repair as necessary.
Step 10.
Was a problem found?
a. Ignition OFF.
b. Disconnect IAT sensor harness terminals.
c. Ignition ON, engine OFF.
7.
8.
d. Connect DVOM across the sensor harness terminals.
Is voltage above 4 volts?
Step 8. Step 9.
Locate and repair intermittent faulty connections or re-
place faulty IAT sensor.
–
Verify
Repair
9.
Locate and repair short to ground in CKT 472.
Repair faulty ECM connections.
Step 10.
–
10.
Index
90-861327--1
OCTOBER 1999
Page 5G-67
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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