Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC2011SAVANA SPECIAL 4.8 AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 4 (ENGINE CONTROLS AND FUEL - 6.6L (LGH) - DTC P0016 THROUGH DTC P11DC)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0090TESTINGCIRCUIT/SYSTEM TESTING
2011 GMC Savana Special 4.8 A
Circuit/System Testing
2011 GMC Savana Special 4.8 ASECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
- Ignition OFF, disconnect the 12-way harness connector at the engine harness jumper. Refer to Inline Harness Connector End ViewsNOTE:
Testing for steps 2-7 is performed on the ECM side of the harness connector.
- Connect a test lamp between the high control circuit terminal 5 and ground.
- Ignition ON, verify the test lamp illuminates for 1-2 s and then turns OFF.
- If the test lamp does not illuminate, test the high control circuit for an open, high resistance or short to ground. If the circuit tests normal, replace the K20 engine control module.
- If the test lamp remains illuminated, test the high control circuit for a short to B+. If the circuit tests normal, replace the K20 engine control module.
- Ignition ON, verify that a test lamp does not illuminate between the low control circuit terminal 6 and ground.
- If the test lamp illuminates, test the low control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
- Ignition OFF, ECM powered down. Connect a test lamp between the low control circuit terminal 6 and B+.
- Ignition ON, verify the test lamp illuminates.
- If the test lamp does not illuminate, test the low control circuit for an open or high resistance. If the circuit tests normal, replace the K20 engine control module.
- Ignition OFF, Observe that the test lamp flashes 2 times and remains OFF until the ECM is powered down.
- If the test lamp does not flash 2 times and turn OFF, test the low control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
- Disconnect the harness connector at the Q45A fuel pressure regulator 1. Test, inspect and repair the items listed below. If all items test normal, replace the Q45A fuel pressure regulator 1.
- Poor connection at the Q45A fuel pressure regulator 1,
- Open, high resistance or shorted fuel pressure regulator 1 high control circuit.
- Open, high resistance or shorted fuel pressure regulator 1 low control circuit.
NOTE:
Testing for this step is performed on the engine side of the harness connector.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.