Checks
| Action
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DEFINITION: Fuel economy, as measured by actual road tests and several tanks
of fuel, is noticeably lower than expected. Also, the economy is noticeably lower
than it was on this vehicle at one time, as previously shown by actual road tests.
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Preliminary Checks
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| • | Check air cleaner filter for dirt or being plugged. |
| • | Visually and physically check: vacuum hoses for splits, kinks, and proper
connections. |
| • | Check the driving habits of the owner. |
| • | Is the A/C ON full time (Defroster mode ON)? |
| • | Are the tires at the correct pressure? |
| • | Are excessively heavy loads being carried? |
| • | Is the acceleration too much, too often? |
| • | Suggest to the owner to fill the fuel tank and recheck the fuel economy. |
| • | Suggest to the driver to read the Important Facts on Fuel Economy in the
Owner Manual. |
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Fuel System Checks
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| • | Check the fuel type and quality. |
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Cooling System Checks
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| • | Check the engine coolant level. |
| • | Check the engine thermostat for always being open or for the wrong heat
range. |
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Additional Checks
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| • | Check the transmission shift pattern. |
| • | Check the torque converter Clutch (TCC) operation. Refer to
Torque Converter Diagnosis
in Automatic Transmission-4L80-E.
When the TCC is commanded ON, a scan tool should indicate an RPM drop. |
| • | Check the Service Bulletins for control module software updates. |
| • | Check for dragging brakes. |
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