DTC P2603

DTC P2603: Electric Engine Coolant Pump Circuit High Voltage

General Description

Courtesy of HONDA, U.S.A., INC.

The electric engine coolant pump varies revolution speed according to the outputs signal. The PCM outputs signal (EWPC) to the electric engine coolant pump and feeds back the revolution speed (EWP REV) from the electric engine coolant pump to control the revolution speed. Since the flow rate of the pump is in proportion to the revolution speed, the flow rate increases as the revolution speed is raised. If the electric engine coolant pump revolution speed is more than a specified value continuously for the prescribed time when the PCM outputs stop signal to the electric coolant pump, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	6.0 seconds or more
DTC Type	Two drive cycles, MIL on

Enable Conditions

Condition	Minimum	Maximum
Electric engine coolant pump drive duty	-	8 %
Vehicle	ON mode

Malfunction Threshold

The electric engine coolant pump is at 600 RPM or more for at least 6.0 seconds

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

Electric engine coolant pump EWPC line short to power
Electric engine coolant pump EWPC line open
Electric engine coolant pump failure
PCM failure

Confirmation Procedure

Operating Condition

Enter the maintenance mode, then start the engine.

With the HDS

Do the ELECTRIC WATER PUMP TEST in the INSPECTION MENU with the HDS.

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.