Transfer Case Leak Diagnosis

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Cause	Correction
GM P/N 12378514 (Canadian P/N 88901045) Hypoid Gear Oil has ultraviolet dye already included within the oil. Drain and fill the unit with new oil before using the J 28428-E black light, when inspecting for leaks. Ultraviolet dye J 28431-6 is not approved for use.
Restricted or damaged ventilation tube assembly	Replace the ventilation tube as required.
Worn, scored, or missing drain and/or fill plug sealing washers	Install new sealing washers and tighten the plugs per specifications.
Leaking vehicle speed sensor or O-ring seal	Replace the sensor and/or O-ring as required.
Worn or damaged driven shaft oil seal	Replace the driven shaft oil seal and output flange as required.
Cut or damaged drive shaft housing O-ring seal	Replace the O-ring seal as required.
Worn drive shaft oil seals Worn or damaged drive shaft oil seals may be detected by a fluid leak at the vent hole area on the bottom of the case. A red colored fluid indicates a transaxle fluid leak and a clear or brown colored fluid indicates a hypoid gear oil leak.	Replace the oil seals and the drive/driven shafts as required.
Worn or damaged right side axle shaft oil seal	Replace the axle shaft oil seal and axle shaft as required.
Cut or damaged transaxle assembly-to-transfer case O-ring seals	Replace the O-ring seals as required.
Cases or housings porosity or leaking seal surfaces	Replace the cases and housings as required and reseal the assembly.