Heater Water Pump Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: Heater Water Pump Circuit

Heater Water Pump Circuit

DESCRIPTION

The heater water pump assembly sends engine coolant to the heater core assembly while the engine is stopped to prevent heater effectiveness from becoming low. Directed by the air conditioning amplifier assembly, hybrid vehicle control ECU operates the water pump relay and drives the heater water pump assembly.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Select the item below in the Active Test and then check that the relay operates.

Active Test / Air Conditioner





OK:
Heater water pump operates smoothly.

Result





C -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
2. INSPECT FUSE (A/C W/P)
(a) Remove the A/C W/P fuse from the main body ECU LH.
(b) Measure the resistance of the fuse.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.
3. INSPECT AIR CONDITIONING WATER PUMP RELAY (Marking: A/C W/P)




(a) Remove the water pump relay from the engine room No. 1 relay block.
NOTICE:
As the water pump relay is connected to the relays and fuses in the other systems, remove it with the power switch OFF. (A DTC may be output if the power switch is ON (IG).)
(b) Measure the resistance of the relay.
Standard resistance:






NG -- REPLACE WATER PUMP RELAY
OK -- Continue to next step.
4.
CHECK WIRE HARNESS (HYBRID VEHICLE CONTROL ECU - BATTERY)




(a) Install the water pump relay.
(b) Disconnect the A54 hybrid vehicle control ECU connector.
(c) Measure the voltage of the wire harness side connector.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5.
CHECK WIRE HARNESS (A/C W/P FUSE - AIR CONDITIONING WATER PUMP RELAY)




(a) Remove the water pump relay from the engine room No. 1 relay block.
(b) Measure the voltage of the air conditioning water pump connector.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6.
CHECK WIRE HARNESS (HEATER WATER PUMP - BODY GROUND)




(a) Disconnect the A56 heater water pump connector.
(b) Measure the resistance of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7.
CHECK WIRE HARNESS (AIR CONDITIONING WATER PUMP RELAY - HEATER WATER PUMP)




(a) Remove the water pump relay from the engine room No. 1 relay block.
(b) Disconnect the A56 heater water pump connector.
(c) Measure the resistance of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
8.
INSPECT HEATER WATER PUMP ASSEMBLY




(a) Remove the heater water pump.
(b) Connect the battery's positive (+) lead to terminal 2 (+B) and negative (-) to terminal 1 (-) of the heater water pump connector.
OK:
Heater water pump operates smoothly.
NOTICE:
Complete operation within 10 seconds if there is no water in the heater water pump assembly.

NG -- REPLACE HEATER WATER PUMP ASSEMBLY
OK -- REPLACE HYBRID VEHICLE CONTROL ECU