SHIFT CONDITIONS / THM 700-R4 ADJUST T.V. CABLE/NOT CORRECT

VEHICLES AFFECTED ----------------- This information applies to all 1983 2000 models equipped with engine driven vacuum pumps. This includes all vehicles equipped with cruise control and all early production vehicles having vehicle identification numbers with the last eight characters less than D7273693. Vehicles built after this breakpoint were equipped with the same vacuum bleed valve which is a part of this bulletin.

CONDITION

Some complaints of hard starting, rough idle, black smoke, and/or intermittent check engine light accompanied by a Code 33 (MAP sensor) can be attributed to the EGR valve binding in the wide open position after engine shutdown.

DIAGNOSIS

To determine if the EGR valve and related systems are functioning properly, follow the diagnostic chart shown on the reverse side.

The following is recommended as a replacement for the Correction Section in this bulletin:

CORRECTION

1. If the EGR valve is closed with the key on and the engine off, the EGR valve is functioning properly. Install a vacuum bleed valve (part number 14079541) and proceed to the MAP sensor diagnostics.

2. If the EGR valve fails to close with the key on and the vacuum signal line removed, replace the EGR valve and install a vacuum bleed valve (part number 14079541).

3. If the EGR valve closes with the key on when the vacuum signal line is removed, inspect the EGR solenoid valve for proper function (refer to Chart 8 in the EFI Diagnostic Section of the Service Manual) and install a vacuum bleed valve (part number 14079541).

Use applicable labor operation.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.