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 CARSECTION 550 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U1001-U1254CIRCUIT/SYSTEM TESTING
2006 Isuzu Ascender S, 5.3 M, 4WD
Circuit/System Testing
2006 Isuzu Ascender S, 5.3 M, 4WDSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Envoy and 2009 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Use the schematic to identify the following:
- Control modules the vehicle is equipped with
- Control module locations on the class 2 serial data circuit
- The control modules B+, ignition, and ground
- Determine the module that is not communicating. Refer to Control Module U Code ListΒ .
- Ignition OFF, disconnect the necessary harness connector of the module that is not communicating.
- Test for less than 5 Ξ© between each ground circuit terminal and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
- If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
- Ignition OFF for 60 seconds, test for less than 5 Ξ© between the serial data circuit terminals and the DLC terminal class 2 serial data terminal 2
- If greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module and a module setting the DTC or a serial data splice pack.
- If all circuits test normal, replace the control module that is not communicating.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.