2010 Cadillac CTS Sedan AWD V6-3.6L Page 2002
瀚慖f the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle).
2. Ignition OFF, disconnect the harness connector at the G12 fuel pump.
3. Ignition ON, test for less than 5.0 ohm between the G12 fuel pump low reference circuit terminal 2 and ground.
瀚慖f greater than the specified range, test the G12 fuel pump low reference circuit for a high resistance. If the circuit tests normal, replace
the K27 fuel pump control module.
4. Ignition OFF, install a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
5. Ignition ON, command the Fuel Pump Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between
the commanded states.
瀚慖f the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 fuel pump control
module.
瀚慖f the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace
the K27 fuel pump control module.
6. Perform the Fuel System Diagnosis (See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Component
Tests and General Diagnostics/Fuel System Diagnosis) to verify proper fuel pressure.
瀚慖f the fuel pressure is not normal, replace the G12 fuel pump
7. If all circuits test normal, replace the K27 fuel pump control module.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Fuel Tank Fuel Pump Module Replacement - Right Side (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Pump/Service
and Repair/Fuel Tank Fuel Pump Module Replacement - Right Side)
* Control Module References (See: Testing and Inspection/Programming and Relearning)for fuel pump control module replacement, setup,
and programming
P2636
DTC P2636
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P2636
- Fuel Pump 2 Flow Insufficient
Circuit Description
The fuel tank on this vehicle is equipped with 2 fuel level sensors, one for each reservoir of the fuel tank. Fuel is transferred from the left side of the
fuel tank to the right side of the fuel tank in order to ensure all of the usable fuel volume is available. The fuel pump supplies a small amount of
pressurized fuel to the siphon jet pump through the fuel feed pipe. The pressurized fuel creates a venturi action inside the siphon jet pump. The
venturi action causes the fuel to be drawn out of the left side of the fuel tank. Fuel is then transferred from the left side of fuel tank to the right side
of fuel tank through the internal fuel transfer tube. This diagnostic tests for too large of a difference in fuel level between the left and right side of
the fuel tank. The DTC sets if the control module determines that the right side fuel level is less than a predetermined amount of the left side fuel
level.
The following table illustrates the difference between fuel level, resistance, and voltage:
