For 1990-2009 cars

# CHUGGLE AT 35-45 MPH WITH TCC ENGAGED-REVISED PROM RELEASED

#### SUBJECT: CHUGGLE AT 56-72 KPH WITH TORQUE CONVERTER CLUTCH ENGAGED (REVISED PROM)

VEHICLES AFFECTED: 1986 "A,C,H" AND 1987 "A,C" MODELS EQUIPPED WITH 3.8L (WITHOUT OPTION NM5) -----------------------------------------------------------------------------

Some owners of 1986 and 1987 A, C, and H models equipped with 3.8L (code B and 3) engine and standard axle ratio may experience a condition of chuggle at 56-73 KPH with the torque converter clutch engaged. If the condition cannot be repaired using currently published service and diagnostic procedures, it may be necessary to install a revised calibration prom.

The proms are currently available through CANSPO under the following numbers.

PROM PROM PROM *AXLE *EMISSION SERVICE SCANNER BROADCAST YEAR SERIES RATIO TYPE PART NO. I.D. CODE CODE ---- ------ ----- --------- -------- --------- --------- 1986 A F17/2.84 (NA5/NB2) 16158376 8394 AWWY

1986 H FP3/2.73 (NA5/NB2) 16158375 8404 AWWZ

1986 C F17/2.84 (NA5/NB2) 16158377 8384 AWWX (Non T-Type models only)

1987 C FP3/2.73 (NA5/NB2) 16158373 8414 AWXA

1987 A F17/2.84 (NA5/NB2) 16158372 8424 AWXB

*N.B. - Axle Ratio sales code ID and emissions type Code 10 may be located on the deck lid decal.

NA5 - Federal Emission System NB2 - California Emission System NM5 - Canadian Emissions System i.e. - 1987 "H" series Sold in Canada

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.