MORE THAN NORMAL BLACK SMOKE AT IDLE (NEW PROM)

VEHICLES AFFECTED: 1988 AND EARLY 1989 C/K/R/V/G TRUCKS W/6.2L (VIN C) DIESEL

Comments have been received of more than normal black smoke at idle on the above mentioned vehicles.

To correct this black smoke condition, the Engine Control Module (ECM) calibration has been modified to enhance the regulation of the Exhaust Gas Recirculation circuit at idle. Listed below are the replacement PROM's required to service the 1988-89 model vehicles.

Replacement Broadcast Scanner PROM --------- ------- ----------- Code I.D. P/N Model ---- ---- --- -----

1988

APYC Visual 16133376 R/V C/K/G ALL MODELS Inspection 1989 ---- APXY 3381 16133879 R/V 1 AND MD8 G2 AND MY6

APXZ 3391 **16141815 C/K 1,2 AND M20 Cl AND MD8

APYA 3401 16133888 C2 AND MD8 K1,2 AND MD8 G2 AND MD8

1988 vehicles require visual inspection of the PROM Broadcast label for ECM Identification (I.D.).

Tech I Scan tool may be used to identify ECM calibration on 1989 vehicles.

Current service procedure for PROM replacement should be used.

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.