Pinpoint Test H: Insufficient, Erratic Or No Heat
WARNING: This page is about a different variant/trim than selected.
- H1 CHECK FOR CORRECT ENGINE COOLANT LEVEL
- Ignition OFF.
- Check the engine coolant level when hot and cold.
- Is the engine coolant at the correct level (hot/cold) as indicated on the engine coolant recovery reservoir?
- H2 CHECK THE ENGINE COOLING SYSTEM FOR LEAKS
- Pressure test the cooling system for leaks. Refer to COOLING SYSTEM PRESSURE TEST .
- Does the engine cooling system leak?
- Yes: REPAIR the engine coolant leak. TEST the system for normal operation.
- No: FILL and BLEED the cooling system. REFER to COOLING SYSTEM DRAINING, FILLING AND BLEEDING . After filling and bleeding the cooling system, GO to H3.
- H3 CHECK FOR COOLANT FLOW TO THE HEATER CORE
- Start the engine and let the engine idle until it shuts down automatically,
- Select FLOOR mode.
- Set the temperature to the warmest setting.
- Select the lowest blower motor setting.
- Using a suitable temperature measuring device, check the heater core inlet hose to see if it is hot.
- Is the heater core inlet hose hot?
- H4 CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE
- Using a suitable temperature measuring device, measure the heater core outlet hose temperature.
- Is the heater core outlet hose temperature similar to the inlet hose temperature (within approximately 6-17°C [10-30°F])?
- Yes: REFER to CLIMATE CONTROL SYSTEM and diagnose for temperature control is inoperative/does not operate correctly.
- No: INSTALL a new heater core. TEST the system for normal operation.
- H5 CHECK FOR COOLANT FLOW TO THE AUXILIARY COOLANT FLOW PUMP
- Using a suitable temperature measuring device, check the auxiliary coolant flow pump inlet hose to see if it is hot.
- Is the auxiliary coolant flow pump inlet hose hot?
- Yes: GO to H6.
- No: REFER to COOLANT FLOW DIAGRAM to check cooling system function.
- H6 CHECK CIRCUIT CHC01 (BN/YE) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Coolant Flow Pump C1450.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger - PCM.
- Toggle the Heater Pump Commanded (HPUMP) output command ON.
- Measure the voltage between auxiliary coolant flow pump C1450-2, circuit CHC01 (BN/YE), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes: GO to H7.
- No:
CARRY OUT the auxiliary coolant flow pump relay component test.
Refer to COMPONENT TESTING - HYBRID for component testing.
If the relay tests OK, GO to H8.
- H7 CHECK CIRCUIT GD121 (BK/YE) FOR GROUND
- Ignition OFF.
- Measure the voltage between auxiliary coolant flow pump C1450-1, circuit GD121 (BK/YE), harness side and auxiliary coolant flow pump C1450-2, circuit CHC01 (BN/YE), harness side.
- Is the voltage greater than 10 volts?
- Yes: INSTALL a new auxiliary coolant flow pump. REFER to REMOVAL AND INSTALLATION . TEST the system for normal operation.
- No: REPAIR circuit GD121 (BK/YE) for an open. TEST the system for normal operation.
- H8 CHECK THE AUXILIARY COOLANT FLOW PUMP RELAY VOLTAGE SUPPLY
- Ignition OFF.
- Disconnect: Auxiliary Coolant Flow Pump Relay.
- Ignition ON.
- Measure the voltage between ground and auxiliary coolant flow pump relay socket, circuit SBB13 (GY/RD).
- Is the voltage greater than 10 volts?
- Yes: REPAIR circuit CHC01 (BN/YE) for an open. TEST the system for normal operation.
- No: VERIFY Battery Junction Box (BJB) fuse 13 (15A) is OK. If OK, REPAIR circuit SBB13 (GY/RD) for an open. TEST the system for normal operation. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.