2010 Cadillac CTS Sedan AWD V6-3.6L Page 990
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
1. Engine idling, observe the Fuel Rail Pressure Sensor parameter with a scan tool. The pressure should be approximately 3.5-5.5 MPa (508-798
psi).
2. Command an increase and decrease in fuel rail pressure with a scan tool. Observe the scan tool Fuel Rail Pressure Sensor parameter. The
Fuel Rail Pressure Sensor should increase or decrease with each command.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF.
2. Disconnect the harness connector at the G18 high pressure fuel pump.
3. Engine operating, verify that a test lamp flashes between the low control circuit terminal 1 and B+.
瀚慖f the test lamp is always ON, test the low control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
瀚慖f the test lamp is always OFF, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal,
replace the K20 ECM.
4. Ignition ON, verify that a test lamp illuminates between the high control circuit terminal 2 and ground.
瀚慖f the test lamp does not illuminate, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal,
replace the K20 ECM.
5. If all circuits test normal, test or replace the high pressure G18 fuel pump.
Component Testing
Static Test
1. Ignition OFF, disconnect the harness connector at the high pressure fuel pump.
Note: The DMM and test leads must be calibrated to 0 ohm in order to prevent misdiagnosis.
2. Test for 0.35-0.6 ohm at 20掳C (68掳F) of resistance between low control circuit terminal 1 and high control circuit terminal 2.
瀚慖f the resistance is less than 0.3 ohm or greater than 0.6 ohm, replace the high pressure fuel pump.
3. Test for infinite resistance between each terminal and the high pressure fuel pump housing/case.
瀚慖f not the specified value, replace the high pressure fuel pump.
Dynamic Test
Engine idling, command the Fuel Pressure Control to Increase with a scan tool. The Fuel Rail Pressure Sensor parameter should increase with each
command.
If the Fuel Rail Pressure Sensor parameter does not increase with each command, replace the high pressure fuel pump.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
* Fuel Pump Replacement (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Pump/Service and Repair)
P0091
DTC P0090, P0091, or P0092 (w/LLT)
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
