DTC P2181
Diagnostic Instructions
DTC Descriptor
| DTC P2181: Engine Cooling System
Performance |
Circuit/System Description
The engine control module (ECM) controls the pulse width
modulated (PWM) engine coolant thermostat heater. The thermostat
controls coolant flow and regulates the engine operating
temperature. Ignition voltage is supplied directly to the engine
coolant thermostat heater. The ECM controls the engine coolant
thermostat heater by grounding the control circuit with a solid
state device called a driver.
Conditions for Running the DTC
| • |
DTCs P00B3, P00B4, P0101,
P0102, P0103, P0112, P0113, or P0114 are not set. |
| • |
The engine run time is between
70 s and 22 min. |
| • |
The engine coolant temperature
(ECT) sensor at start up is between -20 to +75°C
(19-140°F). |
| • |
The intake air temperature
(IAT) sensor is between -7 to +75°C (-4 to +167°F).
|
| • |
The engine coolant thermostat
heater command is greater than 50%. |
| • |
The airflow into the engine is
between 11-100 g/s. |
| • |
The DTC runs once per ignition
cycle when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects the engine coolant heated thermostat is stuck
open for 160 s.
Action Taken When the DTC Sets
DTC P2181 is a Type B DTC.
Conditions for Clearing the DTC
DTC P2181 is a Type B DTC.
Diagnostic Aids
| • |
Insufficient vehicle interior
heating is an indication of improper thermostat operation.
|
| • |
The scan tool Desired ECT
Sensor and the ECT Sensor parameters should be within 5°C
(9°F) when the engine is at operating temperature. |
| • |
A resistance condition in the
ECT sensor circuits may cause this DTC. This condition results in a
greater voltage on the ECT sensor signal circuit, which is
interpreted by the ECM as a colder ECT. |
| • |
The engine coolant thermostat
heater has a mechanical fail safe in case of an electrical
condition with the thermostat heater. The mechanical thermostat
will open at approximately 104°C (220°F). The mechanical
thermostat will cycle from approximately 104°C (220°F) to
approximately 98°C (208°F). |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Cooling System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
| 1. |
Ignition ON, observe the DTC
information with a scan tool. DTC P00B3, P00B4, P00B6, P0117,
P0118, P0480, P0481, P0597, P0598, or P0599 should not be
set. |
| 3. |
Engine idling for 15 min with
the A/C OFF. Verify the engine cooing fan is not ON at all times.
Refer to
Cooling Fan Always On . |
|
Note: Depending on
ambient temperature, it may take up to 4 min for the temperature to
increase greater than the specified value.
|
| 4. |
Command the Engine Coolant
Thermostat Heater to 0% with a scan tool. Increase the engine speed
to 3 000 RPM. Observe the scan tool ECT sensor parameter. The
temperature should increase to greater than 102°C
(215°F). |
| ⇒ |
If less than the specified value, replace the E41
Engine Coolant Thermostat Heater. |
| 5. |
Operate the vehicle within the
conditions for running the DTC to verify the DTC does not reset.
You may also operate the vehicle within the conditions that you
observed from the freeze frame/failure records data. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Engine Coolant Thermostat Housing Replacement
|
