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 MANUALSBUICK2013REGAL TURBO PREMIUM, STANDARD TRANSREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 155 (DATA COMMUNICATIONS SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U1818CIRCUIT/SYSTEM TESTING
2013 Buick Regal Turbo Premium, Standard Trans
Circuit/System Testing
2013 Buick Regal Turbo Premium, Standard TransSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2012 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
- The control module location on the powertrain high speed GMLAN serial data circuits
- The control module B+, ignition, ground, accessory wake up serial data 2 and serial data circuit terminals
- Ignition OFF, disconnect harness connector at the K20 engine control module (ECM).
- Test for less than 10 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, ignition ON, 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 K20 ECM for a short to ground. If the circuits test normal, replace the K20 ECM.
- 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 K20 ECM for a short to ground. If the circuits test normal, replace the K20 ECM.
- If equipped, ignition ON, verify that a test lamp illuminates between the accessory wake up serial data circuit terminal and ground.
- If the test lamp does not illuminate, test the entire circuit, including the B+ circuit to the K9 body control module, for an open/high resistance or short to ground. If the circuits test normal, replace the K9 body control module.
- Ignition OFF, disconnect the low voltage harness connector at the control module setting the DTC.
- Ignition OFF and all vehicle systems OFF, all keys at least 3 meters away from vehicle, all access doors closed. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 Ξ© in each serial data circuit between the K20 ECM and the control module setting the DTC.
- If greater than the specified range, test the serial data circuit for an open/high resistance between the K20 ECM and the control module setting the DTC.
- If the circuits test normal, replace the K20 ECM.
NOTE:
Use the schematic to identify the following:
RENDER: 1.0x
NO RELATED
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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.