| Subject: | Fuel Gauge Fluctuation In Park Or Neutral |
| Models: | 2004-2007 Buick Rainier |
| 2002-2009 Cadillac Escalade models |
| 1999-2005 Chevrolet Astro |
| 2002-2009 Chevrolet Avalanche |
| 1998-2009 Chevrolet Blazer Classic and Trailblazer models |
| 2004-2008 Chevrolet Colorado |
| 2001-2005 Chevrolet S10 Crew-Cab and S-10 Pick-Up models |
| 1999-2009 Chevrolet Silverado, Silverado Classic |
| 2000-2009 Chevrolet Tahoe, Suburban |
| 2005-2009 Chevrolet Uplander |
| 1998-2009 GMC Envoy and Envoy Classic models |
| 1998-2005 GMC Jimmy Classic |
| 1999-2009 GMC Sierra and Sierra Classic models |
| 2001-2005 GMC Sonoma and Sonoma Crew-Cab models |
| 2000-2009 GMC Yukon models |
| 2002-2004 Oldsmobile Bravada |
| 1998-2001 Oldsmobile Bravada Classic |
| 2005-2009 Pontiac Montana SV6 |
| 2003-2009 Hummer H2 and H2 SUT models |
| 2006-2009 Hummer H3 models |
This PI was superseded to update models and model years. Please discard PIT3046D
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Fuel gauge may be inaccurate or drops to empty (E) and the low fuel light comes on. Further analysis may reveal that this condition is most apparent when the gauge is at or below the quarter (1/4) tank mark.
Recommendation/Instructions:
Try to duplicate the concern by driving the vehicle a short distance in reverse and then stopping (to make fuel slosh), shifting transmission to park or neutral and then shifting to drive. The fuel gauge will have a tendency to indicate less fuel in the
tank than actually exists. The gauge will take a few minutes to show the actual fuel level. The VCM/PCM is the buffer for the fuel gauge.
- On Automatic Transmissions no buffering takes place when the transmission is in park or neutral. This is a NORMAL characteristic & NO repairs are necessary.
- On Manual Transmissions the fuel gauge is buffered in all gears and neutral. Since the VCM/PCM has no way to know what gear it is in, there is a timer which starts to count up when the clutch is depressed. When this timer reaches its calibrated
value (this value will vary), the filtering switches to the "fast" filter (no buffering). When the clutch is released the filter then switches to the slow filter (system is Buffered). This is a NORMAL characteristic & NO repairs are necessary.
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.
