B3844
DTC B3844
Circuit Description
The hybrid control module (HCM) controls the coolant pump operation by applying voltage to the coolant pump relay control circuit with an internal solid state device called a driver. When the HCM is commanding the relay ON, the voltage of the control circuit should be high, near 12 volts. When the HCM is commanding the relay OFF, the voltage potential of the control circuit should be low, near 0 volts.
The HCM monitors the relay control circuits for the following conditions:
^ Short to ground
^ Short to voltage
^ An open circuit
If the HCM detects an improper voltage level on the coolant pump control circuit driver circuit, then DTC B3844 will set and the driver will be disabled.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3844 Engine Coolant Circulation Pump Circuit
Conditions for Running the DTC
^ The ignition switch is in the RUN or CRANK position.
^ DTC B1422 is not set.
^ The ignition 0 voltage circuit input is within 8-16 volts.
Conditions for Setting the DTC
The HCM determines the state of the coolant pump relay control circuit is shorted to ground, open or shorted to power.
Action Taken When the DTC Sets
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The malfunction indicator lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.
Conditions for Clearing the DTC
^ A current DTC Last Test Failed clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Clear the DTC with a scan tool.
Diagnostic Aids
If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the auxiliary water pump relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the auxiliary water pump relay. The AUX HTR PUMP fuse supplies power to the coil side of the auxiliary water pump relay.
4. Verifies that the HCM is providing ground to the auxiliary water pump relay.
5. Tests if ground is constantly being applied to the auxiliary water pump relay.
