'SERVICE ENGINE SOON' LIGHT CODE 32 (SERVICE PROCEDURE)

VEHICLES AFFECTED: 1988-89 M-VAN W/4.3L

Some 1988 and 1989 model year M-vans equipped with the 4.3L engine (VIN Code Z) may experience a Code 32 - EGR System malfunction. The customer may not experience a change in performance or driveability with a Code 32 set.

If normal diaqnostics do not reveal the cause for Code 32, the following steps should be taken to correct the condition:

1. Check the TCC (Torque Converter Clutch) engagement solenoid for a short-circuit, and correct if the condition is found Refer to the "Fuel and Emission Service Manual Supplement" in the Transmission Controls section for details on TCC diagnostics.

2. If the TCC circuit is operating properly, replace the exhaust oxygen sensor (P/N 25105901).

3. Confirm closed-loop operation of the engine. It is recommended that the following conditions be satisfied during confirmation to determine if the repairs made were effective. These conditions establish the requirements for running a Code 32 test.

Road Load at normal operating temperature

Constant Throttle Position - TPS voltage = 1.3 V (minimum = 1.1 V, maximum = 1.5 V)

Vehicle Speed = 45 mph (minimum = 35 mph, maximum = 55 mph)

Length of test drive - at least 2 to 3 miles

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.