The vehicle has a battery saver feature designed to protect the vehicle's battery.
When any interior lamp is left on and the ignition is turned off, the battery rundown protection system automatically turns the lamp off after 20 minutes.
This prevents draining of the battery.
Electric Power Management
Accessory Power Outlet(s)Chevrolet Cobalt Service & Repair Manual. Timing Chain Tensioner R & R
1.
Disconnect the negative battery cable.
2.
Remove the camshaft cover.
3.
Remove the timing chain tensioner,
Fig. 1.
4.
Remove the seal from the tensioner.
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