TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
90-861326--1 MARCH 1999
Page 5G-39
Code 14 (2 of 3): Engine Coolant Temperature (ECT) Sensor Circuit (Scan) -
Low Temperature Indicated
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
Step 2. DTC 14 will set if signal voltage indicates a coolant temperature below -22
°
F
(-30
°
C).
Step 3. This test simulates a DTC 15. If the ECM recognizes the low voltage signal and
displays a high temperature, the ECM and wiring are OK.
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
–
Step 2
Go to
OBD
System
Check
2
Ignition “ON”
-22
°
F
Does the scan tool display a coolant tem-
perature less than the specified value?
-22 F
(-30
°
C)
Step 3
Step 4
3
1. Ignition “OFF”.
2. Disconnect ECT harness connector.
3. Connect a jumper wire from harness ter-
minal “A” (CKT 814) to harness terminal “B”
(CKT 410).
266
°
F
(130
°
C)
4. Ignition “ON”, engine “OFF”.
Does scan tool display a coolant tempera-
ture above the specified value?
Step 6
Step 5
4
Trouble code 14 is intermittent. Locate and
repair intermittent faulty connections.
–
–
5
Locate and repair open in CKT 410 or CKT
814. If a problem is found, repair as necessary.
Was a problem found?
–
Verify
Repair
Step 7
6
Repair faulty ECT sensor.
Is action complete?
–
–
7
Repair faulty ECM connections or replace
faulty ECM.
Is action complete?
–
–
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