2010 Cadillac CTS Sedan AWD V6-3.6L Page 1056
circuits/connections test normal, test or replace the appropriate Q17 fuel injector.
Component Testing
Note: The DMM and test leads must be calibrated to 0 ohm in order to prevent misdiagnosis.
1. Remove the intake manifold and disconnect the appropriate Q17 fuel injector.
2. Test for 1.9-2.3 ohm at 20掳C (68掳F) between the high voltage supply circuit terminal 2 and the high voltage control circuit terminal 1 at the
Q17 fuel injector.
瀚慖f not within the specified range, replace the Q17 fuel injector.
3. Measure the resistance between each terminal at the Q17 fuel injector and the Q17 fuel injector housing/case. The DMM should display OL
ohm.
瀚慖f less than the specified value, replace the Q17 fuel injector.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Fuel Injector Replacement (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Injector/Service and Repair/Fuel Injector
Replacement)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P0128
DTC P0128 (w/LF1)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0128
- Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature
Circuit Description
The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some
diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air
flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has
warmed up to the closed loop temperature or to the thermostat regulating temperature. If the coolant temperature does not increase normally or does
not reach the closed loop temperature, diagnostics that use the ECT as enabling criteria, may not run when expected.
Conditions for Running the DTC
P0128
* Before the ECM can report DTC P0128 failed, DTC P0117 and P0118 must run and pass.
* DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0114, P0116, P0117, P0118, P0121, P0122, P0123, P0502, or P0503 is
not set.
* The Engine has not run for greater than 30 minutes.
* The Engine run time from a cold start is greater than 2 minutes.
* The ECT is colder than 50掳C (122掳F) at start up.
* The vehicle speed is greater than 8 km/h (5 mph) for more than 2.4 km/h (1.5 miles).
* The Ethanol content of the fuel is less than 87 percent.
* DTC P0128 runs continuously once the above conditions have been met for approximately 15 min.
OR
* DTCs P0116, P0117, or P0118 is not set.
* The block heater is not detected.
* DTC P0128 runs continuously once the above conditions have been met for approximately 8 min.
Conditions for Setting the DTC
