FAULTY TBI DIAGNOSIS & REPAIR TEST PROCEDURES

MODELS AFFECTED: 1987 SKYHAWKS WITH THE LT2 2.OL OHC L-4 ENGINE (VIN CODE K)

In the event a faulty TBI injector is found, the injector resistance must be checked. If the resistance (1987 only) is

(a) less than 1.5 OHMs or (b) Infinity

the injector may have overheated due to a longer than normal duration 12V signal. One example of this would be a grounded ECM harness. If this condition exists, the following must also be checked:

1. Check ECM harness circuit 467 (dark blue wire, connector C2, pin 1 at ECM)for a short to ground and repair as necessary.

2. If no harness short to ground is found, then inspect the ECM label. An ECM with a round sticker with the silver background and blue letters of the Delco Electronics logo may develop an internal ground. If this occurs, a trouble code will not be generated. In this circumstance, both the ECM and the injector must be replaced.

This bulletin is for information only.

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.