Transaxle/Transmission Cooling
Transaxle Cooling
Pinpoint Tests
Pinpoint Test A: MECS (Motor Electronics Cooling System) Cooling Pump Fault
Refer to Wiring Diagram Set 54, Climate Control for schematic and connector information. [1][2]Diagrams By Number
Normal Operation
The Motor Electronics Cooling System (MECS) pump is electrically driven and controlled by the PCM through the MECS (Motor Electronics Cooling System) pump relay. The PCM energizes the MECS (Motor Electronics Cooling System) pump relay by pulling the MECS (Motor Electronics Cooling System) pump output to ground when the ignition is in the ON position.
This pinpoint test is intended to diagnose the following:
- Battery Junction Box (BJB) fuse 13 (15A)
- BJB (Battery Junction Box) fuse 47 (10A)
- MECS (Motor Electronics Cooling System) coolant pump
- Wiring
- MECS (Motor Electronics Cooling System) coolant pump relay
PINPOINT TEST A : MECS (Motor Electronics Cooling System) COOLING PUMP FAULT
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
A1 CHECK FOR DTCs
- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: RETRIEVE.
- Carry out the PCM on-demand self test.
Are DTCs retrieved?
Yes
REFER to Continuously Variable Transmission/Transaxle.
No
GO to A2.
A2 CHECK BJB (Battery Junction Box) FUSE 13 (15A)
- Check fuse: BJB (Battery Junction Box) 13 (15A).
Is the resistance less than 5 ohms?
Yes
GO to A5.
No
GO to A3.
A3 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY POWER SUPPLY CIRCUIT FOR A SHORT TO GROUND
- Disconnect: BJB (Battery Junction Box) Fuse 13 (15A).
- Disconnect: BJB (Battery Junction Box) Relay 44.
- Disconnect: BJB (Battery Junction Box) Relay 42.
- Measure the resistance between the output side of BJB (Battery Junction Box) fuse 13 (15A) and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to A4.
No
REPAIR circuit SBB13 (GY/RD) for a short to ground. CONNECT all components. TEST the system for normal operation.
A4 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP AND HEATER PUMP POWER SUPPLY CIRCUITS FOR A SHORT TO GROUND
- Disconnect: MECS (Motor Electronics Cooling System) Coolant Pump C1466.
- Disconnect: Heater Pump Motor C1450.
- Measure the resistance between BJB (Battery Junction Box) relay 44 pin 5 circuit CE621 (YE/GY), BJB (Battery Junction Box) side and ground.
- Measure the resistance between BJB (Battery Junction Box) relay 42 pin 5 circuit CHC01 (BN/YE), BJB (Battery Junction Box) side and ground.
Are the resistances greater than 10,000 ohms?
Yes
The condition that caused BJB (Battery Junction Box) fuse 13 (15A) to blow is not present. Inspect the wiring harness for an intermittent condition. Repeat test Steps A3 and A4 while wiggling the vehicle wiring harness and visually checking for damage.
No
REPAIR circuit CE621 (YE/GY) or CHC01 (BN/YE) for a short to ground. CONNECT all components. TEST the system for normal operation.
A5 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY (BJB (Battery Junction Box) RELAY 44)
- Carry out the relay component test.
Is MECS (Motor Electronics Cooling System) pump relay (BJB (Battery Junction Box) relay 44) OK?
Yes
GO to A6.
No
INSTALL a new MECS (Motor Electronics Cooling System) pump relay (BJB (Battery Junction Box) relay 44). TEST the system for normal operation.
A6 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY POWER SUPPLY CIRCUIT FOR AN OPEN
- Measure the resistance between BJB (Battery Junction Box) fuse 13 (15A) circuit CE621 (YE/GY), BJB (Battery Junction Box) side and BJB (Battery Junction Box) relay 44 pin 5 circuit CE621 (YE/GY), BJB (Battery Junction Box) side.
Is the resistance less than 5 ohms?
Yes
GO to A7.
No
REPAIR circuit CE621 (YE/GY) for an open. CONNECT all components. TEST the system for normal operation.
A7 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP POWER SUPPLY CIRCUIT FOR AN OPEN
- Measure the resistance between BJB (Battery Junction Box) relay 44 pin 5 circuit CE621 (YE/GY), BJB (Battery Junction Box) side and MECS (Motor Electronics Cooling System) coolant pump C1466-2, circuit CE621 (YE/GY).
Is the resistance less than 5 ohms?
Yes
GO to A8.
No
REPAIR circuit CE621 (YE/GY) for an open. CONNECT all components. TEST the system for normal operation.
A8 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between MECS (Motor Electronics Cooling System) coolant pump C1466-1 circuit GD121 (BK/YE) and ground.
Is the resistance less than 5 ohms?
Yes
GO to A9.
No
REPAIR circuit GD121 (BK/YE). CONNECT all components. TEST the system for normal operation.
A9 CHECK BJB (Battery Junction Box) FUSE 47 (10A)
- Check fuse: BJB (Battery Junction Box) 47 (10A).
Is the resistance less than 5 ohms?
Yes
GO to A10.
No
REPAIR circuit CBK03 (GY) for a short to ground. CONNECT all components. TEST the system for normal operation.
A10 CHECK FOR VOLTAGE SUPPLIED TO BJB (Battery Junction Box) FUSE 47 (10A)
- Disconnect: BJB (Battery Junction Box) Fuse 47 (10A).
- Ignition ON.
- Measure the voltage at the supply side of BJB (Battery Junction Box) fuse 47 (10A).
Is the voltage greater than 10 volts?
Yes
GO to A11.
No
REPAIR circuit CE612 (GY/VT) for an open. CONNECT all components. TEST the system for normal operation.
A11 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY CONTROL POWER SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the output side of BJB (Battery Junction Box) fuse 47 (10A), circuit CBK03 (GY) and BJB (Battery Junction Box) relay 44 pin 1 circuit CBK03 (GY).
Is the resistance less than 5 ohms?
Yes
GO to A12.
No
REPAIR circuit CBK03 (GY) for an open. CONNECT all components. TEST the system for normal operation.
A12 CHECK FOR GROUND AT THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY
- Connect: BJB (Battery Junction Box) fuse 47 (10A).
- Ignition ON.
- Measure the voltage between BJB (Battery Junction Box) relay 44 pins 1 and 2, BJB (Battery Junction Box) side.
Is the voltage greater than 10 volts?
Yes
INSTALL a new MECS (Motor Electronics Cooling System) pump. REFER to Motor Electronics Pump . CONNECT all components. TEST the system for normal operation.
No
GO to A13.
A13 CHECK THE MECS (Motor Electronics Cooling System) COOLANT PUMP RELAY CONTROL GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM (Powertrain Control Module) C175T.
- Measure the resistance between BJB (Battery Junction Box) relay 44 pin 2, BJB (Battery Junction Box) side circuit CE318 (VT) and PCM C175T-49 circuit CE318 (VT).
Is the resistance less than 5 ohms?
Yes
INSTALL a new PCM. CONNECT all components. TEST the system for normal operation.
No
REPAIR circuit CE318 (VT) for an open. CONNECT all components. TEST the system for normal operation.