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 MANUALSISUZU2006ASCENDER S, 5.3 M, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 5 (ENGINE CONTROL SYSTEM - 4.2L - DTC P0135 TO P0418)DTC P0411CIRCUIT/SYSTEM VERIFICATION
2006 Isuzu Ascender S, 5.3 M, 4WD
Circuit/System Verification
2006 Isuzu Ascender S, 5.3 M, 4WDSECTION Circuit/System Verification
WARNING: This page is about a different variant/trim than selected.
- If any other AIR DTCs are set, perform those diagnostics first.
- With the ignition ON and the engine OFF, observe that the AIR pump is not operating.
- If the AIR pump is operating, test for the following:
- A short to voltage in the AIR pump voltage supply circuit
- A faulty AIR pump relay
- A short to ground in the AIR pump relay control circuit
- A faulty control module
- If the AIR pump is operating, test for the following:
- With the ignition ON, the engine OFF, and the AIR pump enabled with a scan tool, observe that the AIR pump is operating.
- If the AIR pump is not operating, test for the following:
- Resistance greater than 2 ohms in the AIR pump voltage supply or ground circuits
- High resistance or a short to ground in either AIR pump relay voltage supply circuit
- High resistance or a short to voltage in the AIR pump relay control circuit
- A faulty AIR pump relay
- A faulty AIR pump
- A faulty control module
- If the AIR pump is not operating, test for the following:
- With the engine running, enable the AIR pump with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 20-25 kPa above barometric pressure (BARO).
- If not equal to approximately 20-25 kPa above BARO, proceed with Circuit/System Testing.
- With the engine running, enable the AIR solenoid with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.
- If not equal to approximately 8-10 kPa above BARO, proceed with Circuit/System Testing.
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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.