Fuel Gauge Reading Is Inaccurate Or Inconsistent - keywords empty full inoperative IP IPC low message sender sending tank unit
| Subject: | Fuel Gauge Reading Is Inaccurate Or Inconsistent |
| Models: | 2006- 2008 Buick Lucerne and Cadillac DTS |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A customer may comment the fuel gauge reading is inaccurate, inconsistent, or is highly variable. The cause may be design characteristics of the fuel tank, sender, and gauge software.
Recommendation/Instructions:
Important: There may be a real tank, sender, electrical, or gauge concern in the vehicle that is causing the fuel gauge not to perform to expectations. Customer concerns that do not conform to the descriptions listed above should be investigated using SI Diagnostic Information and Procedures.
After carefully noting the customer complaint in detail, the following Potential Causes should be considered, to determine if the complaint could be remedied by making a repair to the vehicle, or whether providing the customer an explanation of the operation of the gauge and fuel system will be sufficient to explain the complaint.
| • | The fuel level sensing float is in the right rear corner of the tank, to the right of the vehicle's centerline. If a customer fills the vehicle on an incline (either nose down or drivers side low), the fuel gauge may not reach the full mark when the tank is full, resulting in a customer complaint. The angle of the incline that causes this issue can be quite minor. The customer may not notice that the gauge did not reach full, but may notice the low gauge reading shortly after the fill, causing the customer to think the gauge swings excessively |
| • | The fuel gauge has a software filter that is very heavily dampened to prevent frequent swings of the gauge needle due to fuel sloshing in the tank during stop-and-go or aggressive driving. This heavy dampening causes the gauge to require more time to correct itself after the vehicle is parked on a hill or filled on an incline, and subsequently driven off. |
| • | A customer may note that the gauge reads below full at the beginning of a trip (when the car may have been parked nose down or driver-side down), and reads higher at the end of the trip. |
| • | Or the gauge may not read full after a fill, but may come back up to full after a significant period of time. |
| • | These situations can result in customer complaints for gauge inaccuracy or variability. |
| • | Due to the float position and high damping of the fuel gauge, parking on inclines may cause the fuel gauge to read low and thereby induce early illumination of the low fuel warning light and cause inaccurate "driving range" / "distance to empty" displays on the Driver Information Center (trip computer). |
| • | The fuel tank design leaves a significant amount of fuel that cannot be read at the top of the tank. This results in many miles of driving before the gauge needle appears to move potentially causing a customer complaint. |
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
