Rough Engine Idle, Hot, No Load (Recalibrate PCM)

This Bulletin is being revised to update the PCM Part Number. Please discard Corporate Bulletin Number 01-06-04-029 (Section 6 - Engine).

Some owners may comment on poor hot engine idle quality. The condition may occur with the climate control and electrical accessories turned off and the transmission gear selector in Park (P).

In some instances, the PCM fueling strategy may not be optimized during hot engine idle no-load conditions.

Important: Calibrate the PCM only if the vehicle exhibits the described condition and not as part of "preventative maintenance".

1. Verify that no PCM diagnostic trouble codes are stored. If PCM trouble codes are present, proceed with published diagnostic information found in the Service Information Manual. DO NOT proceed further with this bulletin.
2. If no PCM diagnostic trouble codes are present, proceed with the following steps, depending on the model year you are working on:

•	2000 Bonneville - Proceed to Step #3

•	2001 Bonneville - Proceed to Step #4

3. PCM calibrations for 2000 Bonnevilles have been released for service. Reprogram the PCM using Techline version 3.0 or greater of the 2001 model year.
4. For 2001 Bonnevilles built prior to the breakpoint listed at the top of this bulletin, install PCM, P/N 12209624, and calibrate the new PCM using Techline version 3.0 or greater of the 2001 model year.

Parts are currently available from GMSPO.

The Calibrations are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting March 2001, on the TIS 2000 version TIS 03/2001 data update or later.

For vehicles repaired under warranty, use: