DTC P00B7 — LDE, LLU, or 2H0
Diagnostic Instructions
DTC Descriptor
DTC P00B7 00: Engine Coolant Flow
Insufficient
Circuit/System Description
The engine control module (ECM) monitors the temperature of the
radiator coolant temperature (RCT) sensor. The engine coolant
thermostat heater is controlled by the ECM. The ECM controls the
engine coolant thermostat heater with a pulse width modulated (PWM)
signal. The ECM compares the radiator coolant temperature (RCT)
sensor to the engine coolant temperature (ECT) sensor in order to
regulate coolant flow through the radiator.
Conditions for Running the DTC
| • |
DTCs P00B3 00, P00B4 00, P0112 00,
P0113 00, P0117 00, or P0118 00 are not set. |
| • |
The engine run time is greater than
300 s. |
| • |
The engine coolant temperature (ECT) sensor is
greater than 106°C (223°F). |
| • |
The DTC runs once per ignition cycle when the
above conditions are met. |
Conditions for Setting the DTC
The ECM detects the difference between the RCT sensor and the
ECT sensor is greater than 30°C (68°F) when the ECT sensor
is warmer than 117°C (242°F).
Action Taken When the DTC Sets
DTC P00B7 00 is a Type B DTC.
Conditions for Clearing the DTC
DTC P00B7 00 is a Type B DTC.
Diagnostic Aids
| • |
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). |
| • |
A resistance condition in the RCT sensor circuits
may cause this DTC. This condition results in a greater voltage on
the RCT sensor signal circuit, which is interpreted by the ECM as a
colder RCT. |
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
- Ignition ON, observe the DTC information with a scan
tool. DTC P00B3 00, P00B4 00, P0117 00,
P0118 00, P0480 00, P0481 00, P0597 00,
P0598 00, or P0599 00 should not be set.
If a DTC is set, refer to
Diagnostic Trouble Code (DTC) List - Vehicle .
- Verify the coolant in the radiator surge tank is at
the correct level and there are no engine coolant leaks. Refer to
Cooling System Draining and Filling and
Loss of Coolant .
- Verify the engine cooling fan operates. Refer to
Cooling Fan Inoperative .
Note: Depending on ambient
temperature, it may take up to 4 min for the temperature to
decrease less than the specified value.
- Engine idling for 15 min with the A/C OFF.
- Command the Engine Coolant Thermostat Heater to 100%
with a scan tool. Increase the engine speed to 3 000 RPM.
Observe the scan tool ECT sensor parameters. The temperature should
decrease to less than 85°C (185°F).
- 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.
Circuit/System Testing
- Ignition OFF, inspect the cooling system for the
following conditions:
| • |
Obstructed radiator air flow or bent radiator
fins |
| • |
Blocked cooling system passages |
| • |
Radiator hoses that are restricted, collapsed, or
deteriorated |
| • |
Loss of cooling system pressure |
| • |
Cylinder head or an engine block that is cracked
or plugged |
- If you find any of the above conditions, repair as
necessary.
- If all conditions test normal, replace the
E41 Engine Coolant Thermostat Heater.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Engine Coolant Thermostat Replacement
|
