GM Service Manual Online
For 1990-2009 cars only

Harsh Shift 4 to 3 for GMC Truck Yukon XL - 2WD 2007

Checks

Cause

Retainer Ring (533)

Not seated

Spring Assembly (532)

Not acting

Bolt (26)

The oil feed hole is plugged.

Cup Plug (530)

Plugged

Direct Lube Exhaust

Blocked