| Subject: | Automatic Dual Zone HVAC Battery Draw Supplement To 02-01-39-007A |
| Models: | 2004-2006 Buick Rainier |
| 2003-2006 Cadillac Escalade, Escalade EXT |
| 2004-2006 Cadillac Escalade ESV |
| 2002-2006 Chevrolet TrailBlazer, Trailblazer EXT and Trailblazer SS |
| 2003-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe |
| 2002-2006 GMC Envoy, Envoy Denali, Envoy XL and Envoy Denali |
| 2003-2006 GMC Denali, Denali XL, Sierra, Yukon, Yukon XL |
| 2002-2004 Oldsmobile Bravada |
| 2007 Chevrolet Silverado Classic |
This PI was superseded to update Model Years. Please discard PIT3179A.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Additional detail beyond TSB 02-01-39-007A.
Vehicle may have a concern with the battery going dead overnight. The draw can be from 40 to 60 mA. This is due to the HVAC control head staying "awake". Further diagnostics may show that the draw is reduced to approx 5 - 9 mA with either the front HVAC
controller unplugged or HVAC fuse B pulled. Disconnecting (& reconnecting) the battery may result in the draw being gone until the next key cycle. The rear HVAC head is unrelated to this issue.
Recommendation/Instructions:
A draw of approx. 60 mA for 2.5 to 3 hours after vehicle shutdown is normal. The time varies with ambient temperature. However, this should NOT be enough to drain the battery.
DO NOT replace the HVAC control head for a draw of 60 mA (approx) or less.
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.
