Pinpoint Test A: DTC P2600
Climate Control System
Pinpoint Test A: DTC P2600
Refer to Wiring Diagram Set 55 (Fusion/Milan/MKZ, Fusion Hybrid, Milan Hybrid, MKZ Hybrid), Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, voltage is provided to the auxiliary coolant flow pump relay coil through circuit CBK03 (GY). When the HVAC module is ON, a message is sent over the Controller Area Network (CAN) to the PCM. When the PCM receives the message, a ground is provided to the auxiliary coolant flow pump relay coil from the PCM through circuit CH307 (GY/BU), energizing the auxiliary coolant flow pump relay.
An auxiliary coolant flow pump is used only on hybrid vehicles to improve engine coolant circulation at low engine speeds or when the engine is OFF.
The auxiliary coolant flow pump will be disabled when any of the following conditions are present:
- The climate control module is set to the OFF position.
- The ambient temperature is above 32°C (90°F).
- The coolant temperature is less than -10°C (14°F).
- The engine speed is above 4,000 rpm.
For a complete explanation of the auxiliary coolant flow pump refer to heating and ventilation in the Description and Operation portion of Climate Control Description and Operation.
- DTC P2600 (Coolant Pump A Control Circuit / Open) - The DTC sets when the PCM grounds the relay circuit and excessive current draw is detected on the relay circuit. The DTC also sets when the relay circuit is OFF and no voltage is detected on the relay control circuit. The PCM expects to detect voltage coming through the relay coil to the relay circuit when it is not grounding it.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- A/C clutch relay
- PCM
PINPOINT TEST A: DTC P2600
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A1 CHECK THE VOLTAGE TO THE RELAY
- Ignition OFF.
- Disconnect: Auxiliary Coolant Flow Pump Relay.
- Ignition ON.
- Measure the voltage between ground and the auxiliary coolant flow pump relay socket, circuit CBK03 (GY).
- Is the voltage greater than 10 volts?
Yes
CARRY OUT the auxiliary coolant flow pump relay component test.
If the relay tests OK, GO to A2.
No
REPAIR circuit CBK03 (GY) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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A2 CHECK CIRCUIT CH307 (GY/BU) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175t.
- Ignition ON.
- Measure the voltage between ground and PCM C175t-42, circuit CH307 (GY/BU), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH307 (GY/BU) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to A3.
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A3 CHECK CIRCUIT CH307 (GY/BU) FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and PCM C175t-42, circuit CH307 (GY/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to A4.
No
REPAIR circuit CH307 (GY/BU) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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A4 CHECK CIRCUIT CH307 (GY/BU) FOR AN OPEN
- Measure the resistance between auxiliary coolant flow pump relay socket, circuit CH307 (GY/BU) and PCM C175t-42, circuit CH307 (GY/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A5.
No
REPAIR circuit CH307 (GY/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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A5 CHECK THE PCM CONNECTION
- Clear the DTCs.
- Disconnect all the PCM connectors.
- Inspect the module connectors for:
- corrosion.
- pushed-out pins.
- incorrectly seated connector.
- Connect and correctly seat all the PCM connectors.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new PCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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