REDUCED PERFORMANCE AND POWER REPLACE ECM MODULE

Subject: REDUCED PERFORMANCE AND POWER

Model and Year: 1991 U VAN WITH 3.1L ENGINE

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-221-6E, DATED MARCH 1991. VIN BREAKPOINTS HAVE BEEN ADDED. ALL COPIES OF 91-221-6E SHOULD BE DISCARDED

Condition: Some owners of 1991 U-vans with 3.1L (VIN D) engine built prior to vehicle number MT1 23361 may comment about reduced performance and power.

Cause: The ECM (Electronic Control Module) may be incorrectly retarding the engine because of incorrect signal from ESC (Electronic Spark Control) module.

Correction: If normal diagnostics as described in your shop manual (Section 6E2-B-3) do not correct this condition, replace ESC module with P/N 16126761 (Broadcast Code ANRZ).

Parts are currently available from GMSPO.

Use applicable Labor Operations And Times.

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.