| Subject: | Fuel Gauge Fluctuation In Park Or Neutral |
| Models: | 2004-2006 Buick Rainier |
| 2002-2006 Cadillac Escalade, Escalade EXT |
| 2003-2006 Cadillac Escalade ESV |
| 1999-2005 Chevrolet Astro |
| 2002-2006 Chevrolet Avalanche |
| 1998-2004 Chevrolet Blazer Classic |
| 2004-2006 Chevrolet Colorado |
| 2001-2004 Chevrolet S10 Crew-Cab |
| 1998-2003 Chevrolet S-10 Pick-Up |
| 1999-2006 Chevrolet Silverado |
| 2000-2006 Chevrolet Tahoe, Suburban |
| 2002-2006 Chevrolet Trailblazer |
| 1998-2001 GMC Envoy Classic |
| 1998-2004 GMC Jimmy Classic |
| 2001-2003 GMC Sonoma Crew-Cab |
| 2000-2006 GMC Yukon, Yukon XL |
| 2002-2004 Oldsmobile Bravada |
| 1998-2001 Oldsmobile Bravada Classic |
This PI has been revised to add additional models. Please discard PIT3046C.
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 read lower than actual.
The gauge will take a few minutes to show the actual fuel level. The VCM/PCM is the buffer for the fuel gauge.
- On a Automatic Transmission no buffering takes place when the transmission is in park or neutral. This is a NORMAL characteristic & NO repairs are necessary.
- On a 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 releases 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.
