| Subject: | Information on Unstable/Rough/Lumpy Engine Idle, and Low Speed Vehicle Surge, Random Disturbance or Vehicle Shudder |
| Models: | 2004-2005 Buick Rainier |
| 2003-2005 Chevrolet TrailBlazer EXT |
| with 5.3L Engine (VINs P, M -- RPOs LM4, LH6) |
This bulletin is being revised to add the 2005 Saab 9-7X to the models. Please discard Corporate Bulletin Number 04-06-04-076 (Section 06 -- Engine/Propulsion System).
The purpose of this bulletin is to inform the technician of the following conditions:
| • | An unstable/rough/lumpy idle |
| • | A low speed vehicle surge, random disturbance, or shudder |
The low speed vehicle surge, random disturbance, or shudder may be felt by the driver while the vehicle is creeping slowly forward under partial brake apply or coming to a stop with a partial brake apply, with the throttle closed at less than 3.2 km/h
(2 mph). The sensation is similar to a vehicle having extreme lateral runout on the front rotors, although there is no sensation in the brake pedal. The condition may be more pronounced on slight incline or when using the vehicle to tow a trailer and
when the coolant is still cool.
At present, there are no mechanical, electrical or fuel related updates that will eliminate these conditions. These are normal vehicle characteristics and no repairs should be attempted.
