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.
2011 Cadillac STS AWDFACTORY OEM SERVICE PROCEDURE
Circuit/System Testing
- With a scan tool, verify DTC U0100-U0299 or U2105-U2199 is not set as current.
- If DTC is set, refer to DTC U0100-U02FFΒ , or DTC U2105-U2199Β .
- Ignition OFF, test for less then 5 Ξ© between the applicable module ground circuit and ground.
- If greater then the specified range, test the circuit for an open/high resistance.
- Ignition OFF, disconnect the applicable module harness connector.
- Ignition ON, verify a test lamp illuminates between the following circuits of the applicable module and ground.
- The battery positive voltage input circuits.
- The battery positive voltage output circuits.
- The ignition voltage input circuits.
- The ignition voltage output circuits.
- The switched battery positive voltage supply circuits.
- If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit fuse is open, test the circuit for a short to ground. If the circuit tests normal, replace the applicable control module.
- Ignition OFF, test for less then 5 Ξ© between the non-communicating modules GMLAN serial data circuits and the module reporting DTC U0002.
- If greater then the specified range, test the circuit for and open/high resistance.
- If all circuits test normal, replace the applicable control module.
Factory Service Tools
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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.
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