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 U2099CIRCUIT/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.
NOTE:
Use the schematic to determine which control modules are on the BCM communications enable circuit 23, X4.
- Ignition OFF, disconnect the harness connector at the most easily accessible control module on the K9 BCM communication enable circuit.
- Ignition ON, retest for current DTCs. DTC U2099 should remain current.
- If the DTC becomes history, replace the control module that was just disconnected.
- With the prior control modules disconnected, repeat steps 1 and 2 for each control module on the circuit except the K9 BCM.
- Ignition OFF, disconnect the X4 harness connector at the K9 BCM.
- Test for infinite resistance between the serial data communication enable circuit terminal 23 X4 and ground.
- If less than infinite resistance, repair the communication enable circuit for a short to ground.
- If all circuits tests normal, replace the K9 BCM.
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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.