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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 253 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING - 8.1L)FUEL SYSTEMSFUEL PUMP ELECTRICAL CIRCUIT DIAGNOSISTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to step numbers on diagnostic procedure.
- 2 - Command both the ON and OFF states. Repeat the commands as necessary.
- 3 - This step determines if condition is located on coil side or on switch side of the circuit.
- 4 - This step verifies that PCM is providing voltage to fuel pump relay.
- 5 - This step tests for an open in ground circuit to fuel pump relay.
- 6 - This step determines if a voltage is constantly being applied to fuel pump relay.
- 12 - To gain access to the fuel pump connector, the fuel tank may need to be removed.
- 13 - This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
- 15 - Use the same amperage fuse in the jumper as is used to protect the fuel pump circuit.
- 16 - To gain access to the fuel pump connector, the fuel tank may need to be removed.
- 17 - Inspect the ground connection for the fuel pump. Be certain all ground connections are clean and tight.
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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.