| Subject: | Transmission Fluid Leaking From the Vent Pipe |
| Models: | 2006-2007 Buick Ranier |
| 2006-2007 Chevrolet Avalanche, Colorado, Express, Silverado Classic, Suburban, Tahoe, Trailblazer |
| 2006-2007 GMC Canyon, Envoy, Savana, Sierra Classic, Yukon, Yukon XL |
| Equipped with 4L60E, 4L65E, 4L70E Automatic Transmission (RPO M30, M32, M70) |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Transmission fluid leaking from the vent pipe.
Recommendation/Instructions:
When diagnosing this condition it is important to inspect the following areas:
- Input speed sensor (ISS) (250) or ISS plug (248). Check to make sure the ISS or plug is fully seated and the retaining bolt is tight. Check the condition of the sealing O-ring (249).
- Pump cover (215) face. Check for machining imperfections that may allow fluid to leak into the vent circuit (area 45 in SI document 338651) in the cover.
A list of other possible causes of fluid leaking from the vent pipe can be found in SI under Fluid Leak Diagnosis.
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.
