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 MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 529 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT COMMUNICATE WITH LOW SPEED GMLAN DEVICECIRCUIT/SYSTEM TESTING
2006 Chevrolet Cobalt SS, 4D Sedan, Standard
Circuit/System Testing
2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2007 Chevrolet Monte Carlo and 2007 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
- Test for less than 1 ohm of resistance between the DLC ground circuit terminal 5 and ground.
- If greater than 1 ohm, test the ground circuit for open/high resistance.
- Ignition OFF, disconnect the harness connector (splice pack comb) at SP 205. Install a 3-amp fused jumper wire between pin A and pin M of SP 205, harness side.
- Ignition ON, with a scan tool, attempt to communicate with the BCM. Communication should be available.
- If no communication, test the following circuits: serial data circuit for a short to ground, a short to voltage or an open/high resistance between the BCM and DLC, BCM voltage inputs for open/high resistance or short to ground, BCM grounds for open/high resistance. If the circuits test normal, replace the BCM.
- Install another 3-amp fused jumper wire to pin A of SP 205, harness side.
- Use the other end of the jumper wire to connect all other pins, harness side, one at a time and verify that low speed communication remains available to the BCM.
- If low speed communication is interrupted after connecting an individual module at SP 205, test the serial data circuit between SP 205 and the last module connected for a short to ground and short to voltage. If the circuit tests normal, replace the module that caused no communication.
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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.