Jeep Wrangler TJ. Manual - part 90
TEST
ACTION
APPLICABILITY
5
WARNING: MAKE SURE THE ENGINE COOLING SYSTEM IS COOL BE-
FORE REMOVING THE PRESSURE CAP OR ANY HOSE. SEVERE PER-
SONAL INJURY MAY RESULT FROM ESCAPING HOT COOLANT. THE
COOLING SYSTEM IS PRESSURIZED WHEN HOT.
With the DRBIII
t, read and record the ECT Sensor Temperature value.
Using the DRB Temperature Probe #CH7050, measure the engine coolant tempera-
ture.
Is the ECT Sensor value with -15°C (5°F) of the temperature probe reading?
All
Yes
→ Go To 6
No
→ Go To 7
6
Inspect the Temperature sensors for any physical damage.
Inspect the engine coolant. Make sure the coolant is at the proper level. Refer to the
Service Information COOLING.
Make sure the Temperature sensors are properly installed.
Make sure the CMP and CKP sensors are mounted properly. Check the connectors for
any signs of damage.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Refer to any Technical Service Bulletins (TSBs) that may apply.
With the engine running at normal operating temperature, monitor the Temperature
sensor parameters while wiggling the wire harness. Look for parameter values to
change.
Visually inspect the related wire harness. Look for any chafed, pierced, pinched,
partially broken wires and broken, bent, pushed out, or corroded terminals.
CAUTION: NEVER PROBE THE PCM HARNESS CONNECTORS. PROBING
THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMI-
NALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL
MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
Inspect and clean all PCM, engine, and chassis grounds.
Were any problems found during the above inspections?
All
Yes
→ Repair as necessary
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Test Complete.
7
NOTE: Visually inspect both the component and the PCM connectors. Look
for damage, partially broken wires and backed out or corroded terminals
Turn the ignition off.
Disconnect the applicable Temperature Sensor harness connector.
Disconnect the PCM harness connectors.
Ignition on, engine not running.
Measure the voltage of the Signal circuit in the appropriate Temperature Sensor
harness connector.
Is the voltage above 5.2 volts?
All
Yes
→ Repair the short to battery voltage in the Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Go To 8
85
DRIVEABILITY - NGC
P0128-THERMOSTAT RATIONALITY —
Continued