Table of Contents
Advertisement
Symptom:
P0128-THERMOSTAT RATIONALITY
When Monitored and Set Condition:
P0128-THERMOSTAT RATIONALITY
When Monitored: The engine running. During cold start.
Set Condition: The PCM predicts a coolant temperature value that it will compare to the
actual coolant temperature. If the two coolant temperature values are not within 10°C
(50°F) of each other an error is detected. Two Trip Fault.
GOOD TRIP EQUAL TO ZERO
LOW COOLANT LEVEL
OTHER POSSIBLE CAUSES
SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
MONITOR ENGINE COOLANT TEMPERATURE
TEMPERATURE SENSOR VOLTAGE BELOW 1.0 VOLT
SIGNAL CIRCUIT OPEN
SENSOR GROUND CIRCUIT OPEN
SIGNAL CIRCUIT SHORTED TO GROUND
SIGNAL CIRCUIT SHORTED TO SENSOR GROUND
PCM LOW
PCM HIGH
TEST
1
NOTE: If any ECT, AAT, CMP or CKP sensor DTCs have set along with P0128,
diagnose them first before continuing.
NOTE: Ensure that Pinion Factor has been programmed correctly into the
PCM.
Ignition on, engine not running.
With the DRBIII , read DTCs and record the related Freeze Frame data.
Is the Good Trip displayed and equal to zero?
Yes → Go To 2
→ Refer to the INTERMITTENT CONDITION symptom in the
No
POSSIBLE CAUSES
ACTION
Driveability category.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
DRIVEABILITY - NGC
81
APPLICABILITY
All
Advertisement
Table of Contents
