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 859 (ENGINE CONTROLS AND FUEL - 2.2L - DTC P0351 TO DTC P2544)DTC P1682CIRCUIT/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 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition ON, observe the Ignition 1 Signal and the EC Ignition Relay Feedback scan tool parameter to determine which is more than 3 V lower than the other.
- Ignition OFF, remove the relay that corresponds to the scan tool parameter that is more than 3 V lower.
- Connect a 20 A fused jumper wire between B+ and the applicable ignition voltage circuit terminal 30. Ignition ON, verify that the applicable scan tool parameter displays between 9-14 V.
- If the applicable scan tool parameter is less than the specified value, test the ignition voltage circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition OFF, connect a DMM set to the diode setting between the control circuit terminal 86 and ground. Verify the DMM displays OL.
- If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
- Ignition ON, verify the DMM displays less than 1 V.
- If not the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- If all circuits test normal, replace the applicable relay.
NOTE:
The Ignition 1 Signal is supplied by the Run/Crank relay. The EC Ignition Relay Feedback signal is supplied by the powertrain relay.
NOTE:
A resistance of 6 Ξ© or greater in the circuit/underhood fuse block will cause the DTC to set.
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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.